Game gets unresponsive after playing for 10 to 30 minutes

[yandexx]

OK I've played on the the settings that the game auto-suggests:
- Medium textures.
- Medium shadows.
- AF 2x.

The resolution is at 1920x1080.

I've played for 1.5 hours and had no hanging or crashing. And the game also fits into 1GB VRAM with these. If you have hanging/crashing like described in my original post, try this workaround (if you're fine with blurrier textures).

Reasons are still unknown though.

Update [07.11.2015]: It was all good and well for like 4-5 hours (apart from sluggish framerate at times), but at one point later in the game I still had hangs three times, had to kill the process and start from save game.
VRAM usage was at 650 MB. So maybe it's not VRAM swapping after all.