Diagram showing two web app contexts (a main document and worker thread). The main document sends a message to the worker thread, but that thread is blocked on a long task and the message gets delayed.

Making complex web apps faster

Patrick Brosset -

Complex web apps which rely on multiple windows, workers, or iframes can sometimes suffer from performance issues due to delays and congestion in the message-passing system (i.e. when using <code>postMessage</code>). In this article, the Edge team introduces a new API: the Delayed Message Timing API, to deal with this problem. The API provides developers with insights into why messagess got delayed, helping you optimize your app's performance.

Read the article at https://blogs.windows.com/msedgedev/2025/12/09/making-complex-web-apps-faster/