BUG OR ISSUE PERFORMANCE

I’m experiencing an issue that didn’t happen before. The game used to run on ultra settings with a stable 180–170 FPS. However, at some point this changed — although it runs perfectly at first, after a while the FPS start to drop and freezes become more and more frequent. In addition, the audio deteriorates to the point where all system sound stops working.

I’ve already tried several solutions: uninstalling and reinstalling the game, reinstalling NVIDIA graphics drivers, lowering all settings to minimum, and disabling V-Sync, but the problem persists. 

Does anyone know what might be going on or has experienced the same issue?