You have an off-by-one frame rendering error; your camera is not synced with the player (tested on both MacOS and windows). I also got 10s hitching on load on a beefy windows rig -- might be missing some shader compiles on the loading screen.

You're probably optimizing for XR, but 99% of people will experience your app for the first time on a different platform, so it's worth fixing the desktop render path.