diff --git a/src/domain/session/room/timeline/tiles/BaseMessageTile.js b/src/domain/session/room/timeline/tiles/BaseMessageTile.js
index d4bbcbaa..3c20f7f7 100644
--- a/src/domain/session/room/timeline/tiles/BaseMessageTile.js
+++ b/src/domain/session/room/timeline/tiles/BaseMessageTile.js
@@ -125,8 +125,7 @@ export class BaseMessageTile extends SimpleTile {
 
     react(key, log = null) {
         return this.logger.wrapOrRun(log, "react", async log => {
-            const existingAnnotation = await this._entry.getOwnAnnotationEntry(this._timeline, key);
-            const redaction = existingAnnotation?.pendingRedaction;
+            const redaction = this._entry.getAnnotationPendingRedaction(key);
             if (redaction && !redaction.pendingEvent.hasStartedSending) {
                 log.set("abort_redaction", true);
                 await redaction.pendingEvent.abort();
@@ -138,9 +137,16 @@ export class BaseMessageTile extends SimpleTile {
 
     redactReaction(key, log = null) {
         return this.logger.wrapOrRun(log, "redactReaction", async log => {
+            const redaction = this._entry.getAnnotationPendingRedaction(key);
+            if (redaction) {
+                log.set("already_redacting", true);
+                return;
+            }
             const entry = await this._entry.getOwnAnnotationEntry(this._timeline, key);
             if (entry) {
                 await this._room.sendRedaction(entry.id, null, log);
+            } else {
+                log.set("no_reaction", true);
             }
         });
     }
diff --git a/src/matrix/room/BaseRoom.js b/src/matrix/room/BaseRoom.js
index 42dc6162..b1d3f7fc 100644
--- a/src/matrix/room/BaseRoom.js
+++ b/src/matrix/room/BaseRoom.js
@@ -452,23 +452,6 @@ export class BaseRoom extends EventEmitter {
         return observable;
     }
 
-    async getOwnAnnotationEntry(targetId, key) {
-        const txn = await this._storage.readWriteTxn([
-            this._storage.storeNames.timelineEvents,
-            this._storage.storeNames.timelineRelations,
-        ]);
-        const relations = await txn.timelineRelations.getForTargetAndType(this.id, targetId, ANNOTATION_RELATION_TYPE);
-        for (const relation of relations) {
-            const annotation = await txn.timelineEvents.getByEventId(this.id, relation.sourceEventId);
-            if (annotation.event.sender === this._user.id && getRelation(annotation.event).key === key) {
-                const eventEntry = new EventEntry(annotation, this._fragmentIdComparer);
-                // add local relations
-                return eventEntry;
-            }
-        }
-        return null;
-    }
-
     async _readEventById(eventId) {
         let stores = [this._storage.storeNames.timelineEvents];
         if (this.isEncrypted) {
diff --git a/src/matrix/room/timeline/PendingAnnotations.js b/src/matrix/room/timeline/PendingAnnotations.js
index cb85aa5b..38034a00 100644
--- a/src/matrix/room/timeline/PendingAnnotations.js
+++ b/src/matrix/room/timeline/PendingAnnotations.js
@@ -19,35 +19,33 @@ import {getRelationFromContent} from "./relations.js";
 export class PendingAnnotations {
     constructor() {
         this.aggregatedAnnotations = new Map();
+        // this contains both pending annotation entries, and pending redactions of remote annotation entries 
         this._entries = [];
     }
 
     /** adds either a pending annotation entry, or a remote annotation entry with a pending redaction */
-    add(annotationEntry) {
-        const relation = getRelationFromContent(annotationEntry.content);
-        const key = relation.key;
+    add(entry) {
+        const {key} = entry.ownOrRedactedRelation;
         if (!key) {
             return;
         }
         const count = this.aggregatedAnnotations.get(key) || 0;
-        const addend = annotationEntry.isRedacted ? -1 : 1;
-        console.log("add", count, addend);
+        const addend = entry.isRedaction ? -1 : 1;
         this.aggregatedAnnotations.set(key, count + addend);
-        this._entries.push(annotationEntry);
+        this._entries.push(entry);
     }
 
     /** removes either a pending annotation entry, or a remote annotation entry with a pending redaction */
-    remove(annotationEntry) {
-        const idx = this._entries.indexOf(annotationEntry);
+    remove(entry) {
+        const idx = this._entries.indexOf(entry);
         if (idx === -1) {
             return;
         }
         this._entries.splice(idx, 1);
-        const relation = getRelationFromContent(annotationEntry.content);
-        const key = relation.key;
+        const {key} = entry.ownOrRedactedRelation;
         let count = this.aggregatedAnnotations.get(key);
         if (count !== undefined) {
-            const addend = annotationEntry.isRedacted ? 1 : -1;
+            const addend = entry.isRedaction ? 1 : -1;
             count += addend;
             if (count <= 0) {
                 this.aggregatedAnnotations.delete(key);
@@ -60,13 +58,22 @@ export class PendingAnnotations {
     findForKey(key) {
         return this._entries.find(e => {
             const relation = getRelationFromContent(e.content);
-            if (relation.key === key) {
+            if (relation && relation.key === key) {
+                return e;
+            }
+        });
+    }
+
+    findRedactionForKey(key) {
+        return this._entries.find(e => {
+            const relation = e.redactingRelation;
+            if (relation && relation.key === key) {
                 return e;
             }
         });
     }
 
     get isEmpty() {
-        return this._entries.length;
+        return this._entries.length === 0;
     }
 }
diff --git a/src/matrix/room/timeline/Timeline.js b/src/matrix/room/timeline/Timeline.js
index bac47124..1dc5213a 100644
--- a/src/matrix/room/timeline/Timeline.js
+++ b/src/matrix/room/timeline/Timeline.js
@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {SortedArray, MappedList, ConcatList, ObservableArray} from "../../../observable/index.js";
+import {SortedArray, AsyncMappedList, ConcatList, ObservableArray} from "../../../observable/index.js";
 import {Disposables} from "../../../utils/Disposables.js";
 import {Direction} from "./Direction.js";
 import {TimelineReader} from "./persistence/TimelineReader.js";
@@ -101,85 +101,65 @@ export class Timeline {
     _setupEntries(timelineEntries) {
         this._remoteEntries.setManySorted(timelineEntries);
         if (this._pendingEvents) {
-            this._localEntries = new MappedList(this._pendingEvents, pe => {
-                const pee = new PendingEventEntry({pendingEvent: pe, member: this._ownMember, clock: this._clock});
-                this._onAddPendingEvent(pee);
-                return pee;
-            }, (pee, params) => {
-                // is sending but redacted, who do we detect that here to remove the relation?
-                pee.notifyUpdate(params);
-            }, pee => this._onRemovePendingEvent(pee));
+            this._localEntries = new AsyncMappedList(this._pendingEvents,
+                pe => this._mapPendingEventToEntry(pe),
+                (pee, params) => {
+                    // is sending but redacted, who do we detect that here to remove the relation?
+                    pee.notifyUpdate(params);
+                },
+                pee => this._applyAndEmitLocalRelationChange(pee, target => target.removeLocalRelation(pee))
+            );
         } else {
             this._localEntries = new ObservableArray();
         }
         this._allEntries = new ConcatList(this._remoteEntries, this._localEntries);
     }
 
-    _onAddPendingEvent(pee) {
-        let redactedEntry;
-        this._applyAndEmitLocalRelationChange(pee.pendingEvent, target => {
-            const wasRedacted = target.isRedacted;
-            const params = target.addLocalRelation(pee);
-            if (!wasRedacted && target.isRedacted) {
-                redactedEntry = target;
-            }
-            return params;
-        });
-        if (redactedEntry) {
-            this._addLocallyRedactedRelationToTarget(redactedEntry);
+    async _mapPendingEventToEntry(pe) {
+        // we load the remote redaction target for pending events,
+        // so if we are redacting a relation, we can pass the redaction
+        // to the relation target and the removal of the relation can
+        // be taken into account for local echo.
+        let redactionTarget;
+        if (pe.eventType === REDACTION_TYPE && pe.relatedEventId) {
+            const txn = await this._storage.readWriteTxn([
+                this._storage.storeNames.timelineEvents,
+            ]);
+            const redactionTargetEntry = await txn.timelineEvents.getByEventId(this._roomId, pe.relatedEventId);
+            redactionTarget = redactionTargetEntry?.event;
         }
+        const pee = new PendingEventEntry({pendingEvent: pe, member: this._ownMember, clock: this._clock, redactionTarget});
+        this._applyAndEmitLocalRelationChange(pee, target => target.addLocalRelation(pee));
+        return pee;
     }
 
-    _addLocallyRedactedRelationToTarget(redactedEntry) {    
-        const redactedRelation = getRelationFromContent(redactedEntry.content);
-        if (redactedRelation?.event_id) {
-            const found = this._remoteEntries.findAndUpdate(
-                e => e.id === redactedRelation.event_id,
-                relationTarget => relationTarget.addLocalRelation(redactedEntry) || false
-            );
-        }
-    }
 
-    _onRemovePendingEvent(pee) {
-        let unredactedEntry;
-        this._applyAndEmitLocalRelationChange(pee.pendingEvent, target => {
-            const wasRedacted = target.isRedacted;
-            const params = target.removeLocalRelation(pee);
-            if (wasRedacted && !target.isRedacted) {
-                unredactedEntry = target;
-            }
-            return params;
-        });
-        if (unredactedEntry) {
-            const redactedRelation = getRelationFromContent(unredactedEntry.content);
-            if (redactedRelation?.event_id) {
-                this._remoteEntries.findAndUpdate(
-                    e => e.id === redactedRelation.event_id,
-                    relationTarget => relationTarget.removeLocalRelation(unredactedEntry) || false
-                );
-            }
-        }
-    }
-
-    _applyAndEmitLocalRelationChange(pe, updater) {
+    _applyAndEmitLocalRelationChange(pee, updater) {
         const updateOrFalse = e => {
             const params = updater(e);
             return params ? params : false;
         };
+        let found = false;
+        const {relatedTxnId} = pee.pendingEvent;
         // first, look in local entries based on txn id
-        if (pe.relatedTxnId) {
-            const found = this._localEntries.findAndUpdate(
-                e => e.id === pe.relatedTxnId,
+        if (relatedTxnId) {
+            found = this._localEntries.findAndUpdate(
+                e => e.id === relatedTxnId,
                 updateOrFalse,
             );
-            if (found) {
-                return;
-            }
         }
         // now look in remote entries based on event id
-        if (pe.relatedEventId) {
+        if (!found && pee.relatedEventId) {
             this._remoteEntries.findAndUpdate(
-                e => e.id === pe.relatedEventId,
+                e => e.id === pee.relatedEventId,
+                updateOrFalse
+            );
+        }
+        // also look for a relation target to update with this redaction
+        if (pee.redactingRelation) {
+            const eventId = pee.redactingRelation.event_id;
+            const found = this._remoteEntries.findAndUpdate(
+                e => e.id === eventId,
                 updateOrFalse
             );
         }
@@ -231,32 +211,17 @@ export class Timeline {
         for (const pee of this._localEntries) {
             // this will work because we set relatedEventId when removing remote echos
             if (pee.relatedEventId) {
-
-
                 const relationTarget = entries.find(e => e.id === pee.relatedEventId);
                 if (relationTarget) {
-                    const wasRedacted = relationTarget.isRedacted;
                     // no need to emit here as this entry is about to be added
                     relationTarget.addLocalRelation(pee);
-                    if (!wasRedacted && relationTarget.isRedacted) {
-                        this._addLocallyRedactedRelationToTarget(relationTarget);
-                    }
-                } else if (pee.eventType === REDACTION_TYPE) {
-                    // if pee is a redaction, we need to lookup the event it is redacting,
-                    // and see if that is a relation of one of the entries
-                    const redactedEntry = this.getByEventId(pee.relatedEventId);
-                    if (redactedEntry) {
-                        const relation = getRelation(redactedEntry);
-                        if (relation) {
-                            const redactedRelationTarget = entries.find(e => e.id === relation.event_id);
-                            redactedRelationTarget?.addLocalRelation(redactedEntry);
-                        }
-                    }
-                } else {
-                    // TODO: errors are swallowed here
-                    // console.log(`could not find target for pee ${pee.relatedEventId} ` + entries.filter(e => !["m.reaction", "m.room.redaction"].includes(e.eventType)).map(e => `${e.id}: ${e.content?.body}`).join(","));
-                    // console.log(`could not find target for pee ${pee.relatedEventId} ` + entries.filter(e => "m.reaction" === e.eventType).map(e => `${e.id}: ${getRelation(e)?.key}`).join(","));
-                    // console.log(`could not find target for pee ${pee.relatedEventId} ` + entries.map(e => `${e.id}: ${e._eventEntry.key.substr(e._eventEntry.key.lastIndexOf("|") + 1)}`).join(","));
+                }
+            }
+            if (pee.redactingRelation) {
+                const eventId = pee.redactingRelation.event_id;
+                const relationTarget = entries.find(e => e.id === eventId);
+                if (relationTarget) {
+                    relationTarget.addLocalRelation(pee);
                 }
             }
         }
@@ -344,6 +309,7 @@ export class Timeline {
 }
 
 import {FragmentIdComparer} from "./FragmentIdComparer.js";
+import {poll} from "../../../mocks/poll.js";
 import {Clock as MockClock} from "../../../mocks/Clock.js";
 import {createMockStorage} from "../../../mocks/Storage.js";
 import {createEvent, withTextBody, withSender} from "../../../mocks/event.js";
@@ -355,6 +321,14 @@ import {PendingEvent} from "../sending/PendingEvent.js";
 export function tests() {
     const fragmentIdComparer = new FragmentIdComparer([]);
     const roomId = "$abc";
+    const noopHandler = {};
+    noopHandler.onAdd = 
+    noopHandler.onUpdate =
+    noopHandler.onRemove =
+    noopHandler.onMove =
+    noopHandler.onReset =
+        function() {};
+
     return {
         "adding or replacing entries before subscribing to entries does not loose local relations": async assert => {
             const pendingEvents = new ObservableArray();
@@ -384,10 +358,11 @@ export function tests() {
                 content: {},
                 relatedEventId: event2.event_id
             }}));
-            // 4. subscribe (it's now safe to iterate timeline.entries)
-            timeline.entries.subscribe({});
+            // 4. subscribe (it's now safe to iterate timeline.entries) 
+            timeline.entries.subscribe(noopHandler);
             // 5. check the local relation got correctly aggregated
-            assert.equal(Array.from(timeline.entries)[0].isRedacting, true);
+            const locallyRedacted = await poll(() => Array.from(timeline.entries)[0].isRedacting);
+            assert.equal(locallyRedacted, true);
         }
     }
 }
diff --git a/src/matrix/room/timeline/entries/BaseEventEntry.js b/src/matrix/room/timeline/entries/BaseEventEntry.js
index 09132a21..8c449f33 100644
--- a/src/matrix/room/timeline/entries/BaseEventEntry.js
+++ b/src/matrix/room/timeline/entries/BaseEventEntry.js
@@ -34,6 +34,10 @@ export class BaseEventEntry extends BaseEntry {
         return this.isRedacting;
     }
 
+    get isRedaction() {
+        return this.eventType === REDACTION_TYPE;
+    }
+
     get redactionReason() {
         if (this._pendingRedactions) {
             return this._pendingRedactions[0].content?.reason;
@@ -46,7 +50,7 @@ export class BaseEventEntry extends BaseEntry {
         @return [string] returns the name of the field that has changed, if any
     */
     addLocalRelation(entry) {
-        if (entry.eventType === REDACTION_TYPE) {
+        if (entry.eventType === REDACTION_TYPE && entry.relatedEventId === this.id) {
             if (!this._pendingRedactions) {
                 this._pendingRedactions = [];
             }
@@ -55,23 +59,25 @@ export class BaseEventEntry extends BaseEntry {
                 return "isRedacted";
             }
         } else {
-            const relation = getRelationFromContent(entry.content);
-            if (relation && relation.rel_type === ANNOTATION_RELATION_TYPE) {
-                if (!this._pendingAnnotations) {
-                    this._pendingAnnotations = new PendingAnnotations();
+            const relation = entry.ownOrRedactedRelation;
+            if (relation && relation.event_id === this.id) {
+                if (relation.rel_type === ANNOTATION_RELATION_TYPE) {
+                    if (!this._pendingAnnotations) {
+                        this._pendingAnnotations = new PendingAnnotations();
+                    }
+                    this._pendingAnnotations.add(entry);
+                    return "pendingAnnotations";
                 }
-                this._pendingAnnotations.add(entry);
-                return "pendingAnnotations";
             }
         }
     }
     
     /**
-        deaggregates local relation.
+        deaggregates local relation or a local redaction of a remote relation.
         @return [string] returns the name of the field that has changed, if any
     */
     removeLocalRelation(entry) {
-        if (entry.eventType === REDACTION_TYPE && this._pendingRedactions) {
+        if (entry.eventType === REDACTION_TYPE && entry.relatedEventId === this.id && this._pendingRedactions) {
             const countBefore = this._pendingRedactions.length;
             this._pendingRedactions = this._pendingRedactions.filter(e => e !== entry);
             if (this._pendingRedactions.length === 0) {
@@ -81,13 +87,15 @@ export class BaseEventEntry extends BaseEntry {
                 }
             }
         } else {
-            const relation = getRelationFromContent(entry.content);
-            if (relation && relation.rel_type === ANNOTATION_RELATION_TYPE && this._pendingAnnotations) {
-                this._pendingAnnotations.remove(entry);
-                if (this._pendingAnnotations.isEmpty) {
-                    this._pendingAnnotations = null;
+            const relation = entry.ownOrRedactedRelation;
+            if (relation && relation.event_id === this.id) {
+                if (relation.rel_type === ANNOTATION_RELATION_TYPE && this._pendingAnnotations) {
+                    this._pendingAnnotations.remove(entry);
+                    if (this._pendingAnnotations.isEmpty) {
+                        this._pendingAnnotations = null;
+                    }
+                    return "pendingAnnotations";
                 }
-                return "pendingAnnotations";
             }
         }
     }
@@ -120,4 +128,8 @@ export class BaseEventEntry extends BaseEntry {
     async getOwnAnnotationEntry(timeline, key) {
         return this._pendingAnnotations?.findForKey(key);
     }
+
+    getAnnotationPendingRedaction(key) {
+        return this._pendingAnnotations?.findRedactionForKey(key);
+    }
 }
diff --git a/src/matrix/room/timeline/entries/PendingEventEntry.js b/src/matrix/room/timeline/entries/PendingEventEntry.js
index 77f6da93..69cdcedc 100644
--- a/src/matrix/room/timeline/entries/PendingEventEntry.js
+++ b/src/matrix/room/timeline/entries/PendingEventEntry.js
@@ -16,14 +16,16 @@ limitations under the License.
 
 import {PENDING_FRAGMENT_ID} from "./BaseEntry.js";
 import {BaseEventEntry} from "./BaseEventEntry.js";
+import {getRelationFromContent} from "../relations.js";
 
 export class PendingEventEntry extends BaseEventEntry {
-    constructor({pendingEvent, member, clock}) {
+    constructor({pendingEvent, member, clock, redactionTarget}) {
         super(null);
         this._pendingEvent = pendingEvent;
         /** @type {RoomMember} */
         this._member = member;
         this._clock = clock;
+        this._redactionTarget = redactionTarget;
     }
 
     get fragmentId() {
@@ -86,6 +88,24 @@ export class PendingEventEntry extends BaseEventEntry {
         return this._pendingEvent.relatedEventId;
     }
 
+    get redactingRelation() {
+        if (this._redactionTarget) {
+            return getRelationFromContent(this._redactionTarget.content);
+        }
+    }
+    /**
+     * returns either the relationship on this entry,
+     * or the relationship this entry is redacting.
+     * 
+     * Useful while aggregating relations for local echo. */
+    get ownOrRedactedRelation() {
+        if (this._redactionTarget) {
+            return getRelationFromContent(this._redactionTarget.content);
+        } else {
+            return getRelationFromContent(this._pendingEvent.content);
+        }
+    }
+
     getOwnAnnotationId(_, key) {
         // TODO: implement this once local reactions are implemented
         return null;
diff --git a/src/observable/index.js b/src/observable/index.js
index 351c25b8..4c455407 100644
--- a/src/observable/index.js
+++ b/src/observable/index.js
@@ -23,6 +23,7 @@ import {BaseObservableMap} from "./map/BaseObservableMap.js";
 export { ObservableArray } from "./list/ObservableArray.js";
 export { SortedArray } from "./list/SortedArray.js";
 export { MappedList } from "./list/MappedList.js";
+export { AsyncMappedList } from "./list/AsyncMappedList.js";
 export { ConcatList } from "./list/ConcatList.js";
 export { ObservableMap } from "./map/ObservableMap.js";
 
diff --git a/src/observable/list/AsyncMappedList.js b/src/observable/list/AsyncMappedList.js
new file mode 100644
index 00000000..12ef3c42
--- /dev/null
+++ b/src/observable/list/AsyncMappedList.js
@@ -0,0 +1,150 @@
+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import {BaseMappedList, runAdd, runUpdate, runRemove, runMove, runReset} from "./BaseMappedList.js";
+
+export class AsyncMappedList extends BaseMappedList {
+    constructor(sourceList, mapper, updater, removeCallback) {
+        super(sourceList, mapper, updater, removeCallback);
+        this._eventQueue = null;
+    }
+
+    onSubscribeFirst() {
+        this._sourceUnsubscribe = this._sourceList.subscribe(this);
+        this._eventQueue = [];
+        this._mappedValues = [];
+        let idx = 0;
+        for (const item of this._sourceList) {
+            this._eventQueue.push(new AddEvent(idx, item));
+            idx += 1;
+        }
+        this._flush();
+    }
+
+    async _flush() {
+        if (this._flushing) {
+            return;
+        }
+        this._flushing = true;
+        try {
+            while (this._eventQueue.length) {
+                const event = this._eventQueue.shift();
+                await event.run(this);
+            }
+        } finally {
+            this._flushing = false;
+        }
+    }
+
+    onReset() {
+        if (this._eventQueue) {
+            this._eventQueue.push(new ResetEvent());
+            this._flush();
+        }
+    }
+
+    onAdd(index, value) {
+        if (this._eventQueue) {
+            this._eventQueue.push(new AddEvent(index, value));
+            this._flush();
+        }
+    }
+
+    onUpdate(index, value, params) {
+        if (this._eventQueue) {
+            this._eventQueue.push(new UpdateEvent(index, value, params));
+            this._flush();
+        }
+    }
+
+    onRemove(index) {
+        if (this._eventQueue) {
+            this._eventQueue.push(new RemoveEvent(index));
+            this._flush();
+        }
+    }
+
+    onMove(fromIdx, toIdx) {
+        if (this._eventQueue) {
+            this._eventQueue.push(new MoveEvent(fromIdx, toIdx));
+            this._flush();
+        }
+    }
+
+    onUnsubscribeLast() {
+        this._sourceUnsubscribe();
+        this._eventQueue = null;
+        this._mappedValues = null;
+    }
+}
+
+class AddEvent {
+    constructor(index, value) {
+        this.index = index;
+        this.value = value;
+    }
+
+    async run(list) {
+        const mappedValue = await list._mapper(this.value);
+        runAdd(list, this.index, mappedValue);
+    }
+}
+
+class UpdateEvent {
+    constructor(index, value, params) {
+        this.index = index;
+        this.value = value;
+        this.params = params;
+    }
+
+    async run(list) {
+        runUpdate(list, this.index, this.value, this.params);
+    }
+}
+
+class RemoveEvent {
+    constructor(index) {
+        this.index = index;
+    }
+
+    async run(list) {
+        runRemove(list, this.index);
+    }
+}
+
+class MoveEvent {
+    constructor(fromIdx, toIdx) {
+        this.fromIdx = fromIdx;
+        this.toIdx = toIdx;
+    }
+
+    async run(list) {
+        runMove(list, this.fromIdx, this.toIdx);
+    }
+}
+
+class ResetEvent {
+    async run(list) {
+        runReset(list);
+    }
+}
+
+export function tests() {
+    return {
+
+    }
+}
diff --git a/src/observable/list/BaseMappedList.js b/src/observable/list/BaseMappedList.js
new file mode 100644
index 00000000..1ccd4e12
--- /dev/null
+++ b/src/observable/list/BaseMappedList.js
@@ -0,0 +1,77 @@
+/*
+Copyright 2020 Bruno Windels <bruno@windels.cloud>
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import {BaseObservableList} from "./BaseObservableList.js";
+import {findAndUpdateInArray} from "./common.js";
+
+export class BaseMappedList extends BaseObservableList {
+    constructor(sourceList, mapper, updater, removeCallback) {
+        super();
+        this._sourceList = sourceList;
+        this._mapper = mapper;
+        this._updater = updater;
+        this._removeCallback = removeCallback;
+        this._mappedValues = null;
+        this._sourceUnsubscribe = null;
+    }
+
+    findAndUpdate(predicate, updater) {
+        return findAndUpdateInArray(predicate, this._mappedValues, this, updater);
+    }
+
+    get length() {
+        return this._mappedValues.length;
+    }
+
+    [Symbol.iterator]() {
+        return this._mappedValues.values();
+    }
+}
+
+export function runAdd(list, index, mappedValue) {
+    list._mappedValues.splice(index, 0, mappedValue);
+    list.emitAdd(index, mappedValue);
+}
+
+export function runUpdate(list, index, value, params) {
+    const mappedValue = list._mappedValues[index];
+    if (list._updater) {
+        list._updater(mappedValue, params, value);
+    }
+    list.emitUpdate(index, mappedValue, params);
+}
+
+export function runRemove(list, index) {
+    const mappedValue = list._mappedValues[index];
+    list._mappedValues.splice(index, 1);
+    if (list._removeCallback) {
+        list._removeCallback(mappedValue);
+    }
+    list.emitRemove(index, mappedValue);
+}
+
+export function runMove(list, fromIdx, toIdx) {
+    const mappedValue = list._mappedValues[fromIdx];
+    list._mappedValues.splice(fromIdx, 1);
+    list._mappedValues.splice(toIdx, 0, mappedValue);
+    list.emitMove(fromIdx, toIdx, mappedValue);
+}
+
+export function runReset(list) {
+    list._mappedValues = [];
+    list.emitReset();
+}
diff --git a/src/observable/list/MappedList.js b/src/observable/list/MappedList.js
index ddb61384..096a018f 100644
--- a/src/observable/list/MappedList.js
+++ b/src/observable/list/MappedList.js
@@ -15,20 +15,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {BaseObservableList} from "./BaseObservableList.js";
-import {findAndUpdateInArray} from "./common.js";
-
-export class MappedList extends BaseObservableList {
-    constructor(sourceList, mapper, updater, removeCallback) {
-        super();
-        this._sourceList = sourceList;
-        this._mapper = mapper;
-        this._updater = updater;
-        this._removeCallback = removeCallback;
-        this._sourceUnsubscribe = null;
-        this._mappedValues = null;
-    }
+import {BaseMappedList, runAdd, runUpdate, runRemove, runMove, runReset} from "./BaseMappedList.js";
 
+export class MappedList extends BaseMappedList {
     onSubscribeFirst() {
         this._sourceUnsubscribe = this._sourceList.subscribe(this);
         this._mappedValues = [];
@@ -38,14 +27,12 @@ export class MappedList extends BaseObservableList {
     }
 
     onReset() {
-        this._mappedValues = [];
-        this.emitReset();
+        runReset(this);
     }
 
     onAdd(index, value) {
         const mappedValue = this._mapper(value);
-        this._mappedValues.splice(index, 0, mappedValue);
-        this.emitAdd(index, mappedValue);
+        runAdd(this, index, mappedValue);
     }
 
     onUpdate(index, value, params) {
@@ -53,47 +40,24 @@ export class MappedList extends BaseObservableList {
         if (!this._mappedValues) {
             return;
         }
-        const mappedValue = this._mappedValues[index];
-        if (this._updater) {
-            this._updater(mappedValue, params, value);
-        }
-        this.emitUpdate(index, mappedValue, params);
+        runUpdate(this, index, value, params);
     }
 
     onRemove(index) {
-        const mappedValue = this._mappedValues[index];
-        this._mappedValues.splice(index, 1);
-        if (this._removeCallback) {
-            this._removeCallback(mappedValue);
-        }
-        this.emitRemove(index, mappedValue);
+        runRemove(this, index);
     }
 
     onMove(fromIdx, toIdx) {
-        const mappedValue = this._mappedValues[fromIdx];
-        this._mappedValues.splice(fromIdx, 1);
-        this._mappedValues.splice(toIdx, 0, mappedValue);
-        this.emitMove(fromIdx, toIdx, mappedValue);
+        runMove(this, fromIdx, toIdx);
     }
 
     onUnsubscribeLast() {
         this._sourceUnsubscribe();
     }
-
-    findAndUpdate(predicate, updater) {
-        return findAndUpdateInArray(predicate, this._mappedValues, this, updater);
-    }
-
-    get length() {
-        return this._mappedValues.length;
-    }
-
-    [Symbol.iterator]() {
-        return this._mappedValues.values();
-    }
 }
 
 import {ObservableArray} from "./ObservableArray.js";
+import {BaseObservableList} from "./BaseObservableList.js";
 
 export async function tests() {
     class MockList extends BaseObservableList {
diff --git a/src/platform/web/ui/css/themes/element/timeline.css b/src/platform/web/ui/css/themes/element/timeline.css
index b2a425ff..af5fb041 100644
--- a/src/platform/web/ui/css/themes/element/timeline.css
+++ b/src/platform/web/ui/css/themes/element/timeline.css
@@ -243,7 +243,7 @@ only loads when the top comes into view*/
 
 .Timeline_messageReactions button.haveReacted.isPending {
     animation-name: glow-reaction-border;
-    animation-duration: 0.8s;
+    animation-duration: 0.5s;
     animation-direction: alternate;
     animation-iteration-count: infinite;
     animation-timing-function: linear;
diff --git a/src/platform/web/ui/session/room/TimelineList.js b/src/platform/web/ui/session/room/TimelineList.js
index a0ad1c83..74556c57 100644
--- a/src/platform/web/ui/session/room/TimelineList.js
+++ b/src/platform/web/ui/session/room/TimelineList.js
@@ -74,6 +74,7 @@ export class TimelineList extends ListView {
             }
         }
         catch (err) {
+            console.error(err);
             //ignore error, as it is handled in the VM
         }
         finally {