This happens to me whenever I use the inventory screen for too long. The FPS drops to near zero and rarely recovers. I usually have to exit and rejoin.

If you go into windowed mode (Alt + Enter), does it recover? It does for me temporarily, but then crashes back once in full screen again.

I suspect it's related to either 1.3 + a windows update or graphic driver, but it's making things unplayable for now.

In T191594#2802360, @Geez wrote:

Hello Naphta.
Can you please let us know in case you come across reproduction steps or some sort of information on what does trigger this problem?
Regards,
Geez

Hello Geez, I noticed that the drop in fps occurs in several cases: firstly, when you aim at someone with a sniper scope or someone who has a zoom, secondly, when you aim at a capture point, thirdly, when you destroy barriers or trees with a vehicle, fourthly, when you open your map quickly after an action, even with the lowest resolution, the drop in fps persists. I now play constantly in 720p and every hour I have to restart the game and sometimes even my PC. Maybe it could come from a cheater who uses CPU fryers like in Tarkov, I don't know. Sometimes just looking in the wrong place makes you lose all your fps when you appear, also this can happen. I hope this detail will help you fix your game. Sorry for the potential bad translation. Best regards.