Severe FPS Drops (5-10 FPS) in every game mode, even in Menus

I managed to solve the issue thanks to DiogoSousaR10​ and shooteronlinepro​!

For anyone experiencing the same FPS drops:

I turned Vertical Sync ON in both the NVIDIA Control Panel (Important!) and the In-Game Settings (this was OFF before)
I also switched to Borderless Display Mode (not sure if this part helped, but worth mentioning)

After doing this, the game stopped dropping to 5–10 FPS, and everything runs smoothly now. Vertical Sync definitely made the biggest difference! 

Since applying the fix I’ve played:

1 Squad Battles match
1 Kick-Off match
5 RUSH matches

and I didn’t experience the FPS drop issue at all. This was impossible for me before, so it’s a huge improvement. I’ll keep monitoring to be sure, but so far it looks like this solution actually works. Hopefully it helps others too!

NVIDIA Control Panel:

In-Game settings: