After switching from the 5.4.0-47-generic kernel to the 5.4.0-48-generic one, it becomes very very slow for the game to load the levels and related assets from filesystem (textures, etc.), so the issue is likely to no be only about graphical performance.
I forgot to mention:
After switching from the 5.4.0-47-generic kernel to the 5.4.0-48-generic one, it becomes very very slow for the game to load the levels and related assets from filesystem (textures, etc.), so the issue is likely to no be only about graphical performance.