Try running the game with these user.cfg commands in the game directory,
RenderDevice.RenderAheadlimit 4
renderdevice.forcerenderaheadlimit 0
renderdevice.triplebufferingenable 0
renderdevice.vsyncenable 0
postprocess.dynamicaoenable 0
worldrender.motionblurenable 0
worldrender.motionblurforce on 0
worldrender.motionblurfixedshuttertime 0
worldrender.motionblurmax 0
worldrender.motionblurquality 0
worldrender.motionblurmaxsamplecount 0
worldrender.spotlightshadowmapenable 0
worldrender.spotlightshadowmapresolution 256
worldrender.transparencyshadowsenable 0
worldrender.lighttilecspathenable 0
