diff --git a/src/core/GameRunner.ts b/src/core/GameRunner.ts
index 2179d2df5..3e3affd39 100644
--- a/src/core/GameRunner.ts
+++ b/src/core/GameRunner.ts
@@ -173,12 +173,16 @@ export class GameRunner {
     }
 
     // Many tiles are updated to pack it into an array
-    const packedTileUpdates = updates[GameUpdateType.Tile].map((u) => u.update);
+    const tileUpdates = updates[GameUpdateType.Tile];
+    const packedTileUpdates = new BigUint64Array(tileUpdates.length);
+    for (let i = 0; i < tileUpdates.length; i++) {
+      packedTileUpdates[i] = tileUpdates[i].update;
+    }
     updates[GameUpdateType.Tile] = [];
 
     this.callBack({
       tick: this.game.ticks(),
-      packedTileUpdates: new BigUint64Array(packedTileUpdates),
+      packedTileUpdates,
       updates: updates,
       playerNameViewData: this.playerViewData,
       tickExecutionDuration: tickExecutionDuration,
diff --git a/src/core/worker/Worker.worker.ts b/src/core/worker/Worker.worker.ts
index aa61da3de..55c37dda1 100644
--- a/src/core/worker/Worker.worker.ts
+++ b/src/core/worker/Worker.worker.ts
@@ -30,6 +30,12 @@ function gameUpdate(gu: GameUpdateViewData | ErrorUpdate) {
 }
 
 function sendMessage(message: WorkerMessage) {
+  if (message.type === "game_update") {
+    // Transfer the packed tile updates buffer to avoid structured-clone copies and
+    // reduce worker-side memory churn during long runs / catch-up.
+    ctx.postMessage(message, [message.gameUpdate.packedTileUpdates.buffer]);
+    return;
+  }
   ctx.postMessage(message);
 }