http://bugs.winehq.org/show_bug.cgi?id=15868
--- Comment #42 from H. Verbeet hverbeet@gmail.com 2009-01-28 03:17:33 --- Looks like depth buffer precision issues. I probably won't have time to look into this soon. The improved speed is probably due to EXT_vertex_array_bgra support in the newer drivers, which should prevent the vertex shader recompilation.