If anybody's curious, I found that some good settings are TEXTURE_BANDWIDTH_MULT=220 and FIBER_FRAME_TIME_FRACTION=0.40. The first loads the textures faster and the second controls how much of one second is devoted to loading textures. If you have a better computer than mine, which is likely, try putting the former at 400 and the second at 0.45.  ;) With my settings, I'm getting reasonable framerates (no choppiness) and fast texture loading.