[CLIENT] Increasing performance issues on system with long uptime

I recently started leaving my PC on 24/7 for mining, and started noticing some hitching (random high frame time), despite system resources being barely used. Today it got to a point where it was downright unplayable, 500ms+ frame time every second or so. The issue did seem to be fairly rythmic, with extra spikes when I started moving the camera (but oddly not during the movement itself). After a full system restart my FPS went back to a steady 300-400 FPS (170 top before the restart, with again constant hitches). The only program that might be causing some interference is RivaTuner/Afterburner.

My final stats before the restart: 40% CPU 50% RAM 15% GPU (Vsync on) After the restart: 30% CPU 40% RAM 15% GPU (again, Vsync on)

I was also experiencing odd crashes when switching Vsync on, switching to fullscreen, or alt tabbing from fullscreen. These are also gone after the PC restart.

No other games were having issues (steady FPS in WoW with no hitching, for example) and it didn't seem to occur in a practice mode, so it might have something to do with the networking/player code.

Hopefully that's enough info, though I can try to provide more on request.

P.S.: I lost one of my placement matches because of this, so not cool.