Microstutter & almost infinite loading screens

I have not changed anything since last league which had no issues. Now it took ~10 minutes to launch the game, and gameplay has constant stuttering and extremely long loading screens to the point i'll just alt+f4. Settings make no difference.

9800x3d, 4090, 64gb

Edit: now getting Deadlock detected popup

Edit2: deleted shaders from steam & %appdata% and cfg, no effect

Edit3: reinstalled game and seems ok for now