diff --git a/src/matrix/room/timeline/persistence/GapWriter.js b/src/matrix/room/timeline/persistence/GapWriter.js
index d2f93e21..7ff23d42 100644
--- a/src/matrix/room/timeline/persistence/GapWriter.js
+++ b/src/matrix/room/timeline/persistence/GapWriter.js
@@ -26,47 +26,28 @@ export class GapWriter {
         this._fragmentIdComparer = fragmentIdComparer;
         this._relationWriter = relationWriter;
     }
+
+    async _pickNeighbourFragment(txn, duplcateEventIds) {
+        const duplicateEventId = duplcateEventIds[0];
+        const duplicateEvent = await txn.timelineEvents.getByEventId(this._roomId, duplicateEventId);
+        return duplicateEvent.fragmentId;
+    }
+
     // events is in reverse-chronological order (last event comes at index 0) if backwards
     async _findOverlappingEvents(fragmentEntry, events, txn, log) {
-        let expectedOverlappingEventId;
-        if (fragmentEntry.hasLinkedFragment) {
-            expectedOverlappingEventId = await this._findExpectedOverlappingEventId(fragmentEntry, txn);
-        }
-        let remainingEvents = events;
-        let nonOverlappingEvents = [];
+        const eventIds = events.map(e => e.event_id);
+        const duplicateEventIds = await txn.timelineEvents.findOccurringEventIds(this._roomId, eventIds);
+        const nonOverlappingEvents = events.filter(e => !duplicateEventIds.includes(e.event_id));
         let neighbourFragmentEntry;
-        while (remainingEvents && remainingEvents.length) {
-            const eventIds = remainingEvents.map(e => e.event_id);
-            const duplicateEventId = await txn.timelineEvents.findFirstOccurringEventId(this._roomId, eventIds);
-            if (duplicateEventId) {
-                const duplicateEventIndex = remainingEvents.findIndex(e => e.event_id === duplicateEventId);
-                // should never happen, just being defensive as this *can't* go wrong
-                if (duplicateEventIndex === -1) {
-                    throw new Error(`findFirstOccurringEventId returned ${duplicateEventIndex} which wasn't ` +
-                        `in [${eventIds.join(",")}] in ${this._roomId}`);
-                }
-                nonOverlappingEvents.push(...remainingEvents.slice(0, duplicateEventIndex));
-                if (!expectedOverlappingEventId || duplicateEventId === expectedOverlappingEventId) {
-                    // TODO: check here that the neighbourEvent is at the correct edge of it's fragment
-                    // get neighbour fragment to link it up later on
-                    const neighbourEvent = await txn.timelineEvents.getByEventId(this._roomId, duplicateEventId);
-                    if (neighbourEvent.fragmentId === fragmentEntry.fragmentId) {
-                        log.log("hit #160, prevent fragment linking to itself", log.level.Warn);
-                    } else {
-                        const neighbourFragment = await txn.timelineFragments.get(this._roomId, neighbourEvent.fragmentId);
-                        neighbourFragmentEntry = fragmentEntry.createNeighbourEntry(neighbourFragment);
-                    }
-                    // trim overlapping events
-                    remainingEvents = null;
-                } else {
-                    // we've hit https://github.com/matrix-org/synapse/issues/7164, 
-                    // e.g. the event id we found is already in our store but it is not
-                    // the adjacent fragment id. Ignore the event, but keep processing the ones after.
-                    remainingEvents = remainingEvents.slice(duplicateEventIndex + 1);
-                }
+        if (eventIds.length && eventIds.length === duplicateEventIds.length) {
+            // TODO: check here that the neighbourEvent is at the correct edge of it's fragment
+            // get neighbour fragment to link it up later on
+            const neighbourFragmentId = await this._pickNeighbourFragment(txn, duplicateEventIds);
+            if (neighbourFragmentId === fragmentEntry.fragmentId) {
+                log.log("hit #160, prevent fragment linking to itself", log.level.Warn);
             } else {
-                nonOverlappingEvents.push(...remainingEvents);
-                remainingEvents = null;
+                const neighbourFragment = await txn.timelineFragments.get(this._roomId, neighbourFragmentId);
+                neighbourFragmentEntry = fragmentEntry.createNeighbourEntry(neighbourFragment);
             }
         }
         return {nonOverlappingEvents, neighbourFragmentEntry};
diff --git a/src/matrix/storage/idb/stores/TimelineEventStore.ts b/src/matrix/storage/idb/stores/TimelineEventStore.ts
index 535b8f7e..4e94425b 100644
--- a/src/matrix/storage/idb/stores/TimelineEventStore.ts
+++ b/src/matrix/storage/idb/stores/TimelineEventStore.ts
@@ -234,31 +234,25 @@ export class TimelineEventStore {
     // In that case we could avoid running over all eventIds, as the reported order by findExistingKeys
     // would match the order of eventIds. That's why findLast is also passed as backwards to keysExist.
     // also passing them in chronological order makes sense as that's how we'll receive them almost always.
-    async findFirstOccurringEventId(roomId: string, eventIds: string[]): Promise<string | undefined> {
+    async findOccurringEventIds(roomId: string, eventIds: string[]): Promise<string[]> {
         const byEventId = this._timelineStore.index("byEventId");
         const keys = eventIds.map(eventId => encodeEventIdKey(roomId, eventId));
         const results = new Array(keys.length);
-        let firstFoundKey: string | undefined;
-
-        // find first result that is found and has no undefined results before it
-        function firstFoundAndPrecedingResolved(): string | undefined {
-            for(let i = 0; i < results.length; ++i) {
-                if (results[i] === undefined) {
-                    return;
-                } else if(results[i] === true) {
-                    return keys[i];
-                }
-            }
-        }
+        const occuringEventIds: string[] = [];
 
         await byEventId.findExistingKeys(keys, false, (key, found) => {
             // T[].search(T, number), but we want T[].search(R, number), so cast
             const index = (keys as IDBValidKey[]).indexOf(key);
             results[index] = found;
-            firstFoundKey = firstFoundAndPrecedingResolved();
-            return !!firstFoundKey;
+            return false;
         });
-        return firstFoundKey && decodeEventIdKey(firstFoundKey).eventId;
+        for(let i = 0; i < results.length; ++i) {
+            console.log(i, eventIds[i], results[i]);
+            if (!results[i]) continue;
+            occuringEventIds.push(eventIds[i]);
+        }
+        console.log(occuringEventIds);
+        return occuringEventIds;
     }
 
     /** Inserts a new entry into the store. The combination of roomId and eventKey should not exist yet, or an error is thrown.