FPS troubles with 5.3.2

Hi everyone!

I've recently migrated my 5.1.1 VR project to 5.3.2 and even after weeks of looking into it, the FPS is severely impacted.

But here's the catch. It only occurs for one of the maps, and this specific map ran 72 FPS on Quest 2. Now it is down to 45 and no matter what I try, I cannot raise back up.

No obvious errors in the log, other than a few no geometry warnings.

Now this map has a number of meshes imported from OBJ files, so they are less than optimal, but! The very same assets had no trouble when packaged on 5.1.1.

So my question is, has anyone encountered such an issue and How this issue could be mended.