Low FPS after first launch

We are developing an app for oculus quest using Unity that works fine at 72 fps but when I launch the app for the second time the fps fall to 60 fps. If we uninstall and install again, the first time always works at 72 fps and the next times again goes to 60 fps.

It's very strange, I think that maybe the app are generating some kind  of cache and after that the cache does not work well.

Any suggestion about what are happening?

Thanks