I am going to bet that you are overloading your machine. Just from looking at the pic I would say that your resolution can be decreased (lower resolution, means less pixels to render per frame). But there are many other things that are minimal eye candy that I don't find it necessary to run while playing. The newest additions in bump mapping, ground detail, water reflections, shadows, etc I leave turned off and view them later by turning them back on and running filmviewer.
I hope you find your answer soon, because the T34 looks like it should be in the local High School parade or we need a Deathmobile skin from the movie Animal House.