diff --git a/src/components/views/elements/MessageEditor.js b/src/components/views/elements/MessageEditor.js
index 85e170373c..9ff0244564 100644
--- a/src/components/views/elements/MessageEditor.js
+++ b/src/components/views/elements/MessageEditor.js
@@ -23,7 +23,7 @@ import EditorModel from '../../../editor/model';
 import {setCaretPosition} from '../../../editor/caret';
 import {getCaretOffsetAndText} from '../../../editor/dom';
 import {htmlSerializeIfNeeded, textSerialize} from '../../../editor/serialize';
-import {findPreviousEditableEvent, findNextEditableEvent} from '../../../utils/EventUtils';
+import {findEditableEvent} from '../../../utils/EventUtils';
 import {parseEvent} from '../../../editor/deserialize';
 import Autocomplete from '../rooms/Autocomplete';
 import {PartCreator} from '../../../editor/parts';
@@ -133,7 +133,7 @@ export default class MessageEditor extends React.Component {
             if (this._hasModifications || !this._isCaretAtStart()) {
                 return;
             }
-            const previousEvent = findPreviousEditableEvent(this._getRoom(), this.props.event.getId());
+            const previousEvent = findEditableEvent(this._getRoom(), false, this.props.event.getId());
             if (previousEvent) {
                 dis.dispatch({action: 'edit_event', event: previousEvent});
                 event.preventDefault();
@@ -142,7 +142,7 @@ export default class MessageEditor extends React.Component {
             if (this._hasModifications || !this._isCaretAtEnd()) {
                 return;
             }
-            const nextEvent = findNextEditableEvent(this._getRoom(), this.props.event.getId());
+            const nextEvent = findEditableEvent(this._getRoom(), true, this.props.event.getId());
             if (nextEvent) {
                 dis.dispatch({action: 'edit_event', event: nextEvent});
             } else {
diff --git a/src/components/views/rooms/MessageComposerInput.js b/src/components/views/rooms/MessageComposerInput.js
index ba24df6d08..30d7aa3237 100644
--- a/src/components/views/rooms/MessageComposerInput.js
+++ b/src/components/views/rooms/MessageComposerInput.js
@@ -59,7 +59,7 @@ import RoomViewStore from '../../../stores/RoomViewStore';
 import ReplyThread from "../elements/ReplyThread";
 import {ContentHelpers} from 'matrix-js-sdk';
 import AccessibleButton from '../elements/AccessibleButton';
-import { findPreviousEditableEvent } from '../../../utils/EventUtils';
+import {findEditableEvent} from '../../../utils/EventUtils';
 
 const REGEX_EMOTICON_WHITESPACE = new RegExp('(?:^|\\s)(' + EMOTICON_REGEX.source + ')\\s$');
 
@@ -1181,7 +1181,7 @@ export default class MessageComposerInput extends React.Component {
             if (up) {
                 if (!selection.anchor.isAtStartOfNode(document)) return;
 
-                const editEvent = findPreviousEditableEvent(this.props.room);
+                const editEvent = findEditableEvent(this.props.room, false);
                 if (editEvent) {
                     // We're selecting history, so prevent the key event from doing anything else
                     e.preventDefault();
diff --git a/src/utils/EventUtils.js b/src/utils/EventUtils.js
index d7c2285e7b..f8a4dd708c 100644
--- a/src/utils/EventUtils.js
+++ b/src/utils/EventUtils.js
@@ -52,34 +52,29 @@ export function canEditContent(mxEvent) {
         mxEvent.getSender() === MatrixClientPeg.get().getUserId();
 }
 
-export function findPreviousEditableEvent(room, fromEventId = undefined) {
+export function findEditableEvent(room, isForward, fromEventId = undefined) {
     const liveTimeline = room.getLiveTimeline();
     const events = liveTimeline.getEvents();
-    let startFromIdx = events.length - 1;
-    if (fromEventId) {
-        const fromEventIdx = findLastIndex(events, e => e.getId() === fromEventId);
-        if (fromEventIdx !== -1) {
-            startFromIdx = fromEventIdx - 1;
-        }
+    const maxIdx = events.length - 1;
+    const inc = isForward ? 1 : -1;
+    const beginIdx = isForward ? 0 : maxIdx;
+    let endIdx = isForward ? maxIdx : 0;
+    if (!fromEventId) {
+        endIdx = Math.min(Math.max(0, beginIdx + (inc * 100)), maxIdx);
     }
-    const nextEventIdx = findLastIndex(events, e => !shouldHideEvent(e) && canEditContent(e), startFromIdx);
-    if (nextEventIdx !== -1) {
-        return events[nextEventIdx];
+    let foundFromEventId = !fromEventId;
+    for (let i = beginIdx; i !== (endIdx + inc); i += inc) {
+        const e = events[i];
+        // find start event first
+        if (!foundFromEventId && e.getId() === fromEventId) {
+            foundFromEventId = true;
+            // don't look further than 100 events from `fromEventId`
+            // to not iterate potentially 1000nds of events on key up/down
+            endIdx = Math.min(Math.max(0, i + (inc * 100)), maxIdx);
+        } else if (foundFromEventId && !shouldHideEvent(e) && canEditContent(e)) {
+            // otherwise look for editable event
+            return e;
+        }
     }
 }
 
-export function findNextEditableEvent(room, fromEventId = undefined) {
-    const liveTimeline = room.getLiveTimeline();
-    const events = liveTimeline.getEvents();
-    let startFromIdx = 0;
-    if (fromEventId) {
-        const fromEventIdx = findIndex(events, e => e.getId() === fromEventId);
-        if (fromEventIdx !== -1) {
-            startFromIdx = fromEventIdx + 1;
-        }
-    }
-    const nextEventIdx = findIndex(events, e => !shouldHideEvent(e) && canEditContent(e), startFromIdx);
-    if (nextEventIdx !== -1) {
-        return events[nextEventIdx];
-    }
-}