I encountered the same issue with gpt-4o (Version 2024-08-06) in the East US region. This seems to be a recurring pattern where older model versions experience degraded performance or timeouts once a new version is released.
In my case, updating to the latest available model version (2024-11-20) resolved the issue immediately. The latest version is significantly faster and more responsive. If you haven’t already, I’d recommend switching to it to resolve the timeout errors.