diff --git a/roomserver/internal/input/input.go b/roomserver/internal/input/input.go
index a10827a01..f84e2b3ad 100644
--- a/roomserver/internal/input/input.go
+++ b/roomserver/internal/input/input.go
@@ -40,7 +40,7 @@ type Inputer struct {
 
 type inputTask struct {
 	ctx   context.Context
-	event api.InputRoomEvent
+	event *api.InputRoomEvent
 	wg    *sync.WaitGroup
 	err   error // written back by worker, only safe to read when all tasks are done
 }
@@ -120,10 +120,12 @@ func (r *Inputer) InputRoomEvents(
 			roomID = e.Event.RoomID()
 		}
 
-		// Look up the worker, or create it if it doesn't exist.
+		// Look up the worker, or create it if it doesn't exist. This channel
+		// is buffered to reduce the chance that we'll be blocked by another
+		// room - the channel will be quite small as it's just pointer types.
 		w, _ := r.workers.LoadOrStore(roomID, &inputWorker{
 			r:     r,
-			input: make(chan *inputTask),
+			input: make(chan *inputTask, 10),
 		})
 		worker := w.(*inputWorker)
 
@@ -132,7 +134,7 @@ func (r *Inputer) InputRoomEvents(
 		// task has been finished.
 		tasks[i] = &inputTask{
 			ctx:   ctx,
-			event: e,
+			event: &request.InputRoomEvents[i],
 			wg:    wg,
 		}
 
diff --git a/roomserver/internal/input/input_events.go b/roomserver/internal/input/input_events.go
index 69f51f4b8..6ee679da6 100644
--- a/roomserver/internal/input/input_events.go
+++ b/roomserver/internal/input/input_events.go
@@ -38,7 +38,7 @@ import (
 // nolint:gocyclo
 func (r *Inputer) processRoomEvent(
 	ctx context.Context,
-	input api.InputRoomEvent,
+	input *api.InputRoomEvent,
 ) (eventID string, err error) {
 	// Parse and validate the event JSON
 	headered := input.Event
@@ -143,7 +143,7 @@ func (r *Inputer) processRoomEvent(
 
 func (r *Inputer) calculateAndSetState(
 	ctx context.Context,
-	input api.InputRoomEvent,
+	input *api.InputRoomEvent,
 	roomInfo types.RoomInfo,
 	stateAtEvent *types.StateAtEvent,
 	event gomatrixserverlib.Event,