# UNDF: UNDF-2026-000001150
--- a/apps/meteor/server/services/video-conference/service.ts
+++ b/apps/meteor/server/services/video-conference/service.ts
@@ -529,12 +529,14 @@ export class VideoConferenceService extends ServiceClassInternal implements IVid
 	private async endDirectCall(call: IDirectVideoConference): Promise<void> {
 		const params = { rid: call.rid, uid: call.createdBy._id, callId: call._id };

 		// Notify the caller that the call was ended by the server
 		this.notifyUser(call.createdBy._id, 'end', params);

 		// If the callee hasn't joined the call yet, notify them that it has already ended
 		const subscriptions = await Subscriptions.findByRoomIdAndNotUserId(call.rid, call.createdBy._id, {
 			projection: { 'u._id': 1, '_id': 0 },
 		}).toArray();

+		// Build a Set so the joined-user lookup is O(1) per subscription
+		// instead of O(U) per subscription (O(S*U) overall) via Array.find().
+		const joinedUserIds = new Set(call.users.map(({ _id }) => _id));
 		for (const subscription of subscriptions) {
 			// Skip notifying users that already joined the call
-			if (call.users.find(({ _id }) => _id === subscription.u._id)) {
+			if (joinedUserIds.has(subscription.u._id)) {
 				continue;
 			}

 			this.notifyUser(subscription.u._id, 'end', params);
 		}
 	}