Thanks! I'd already applied a) (the default is NoCache I think). I just applied b), and it sped things up a little. I'm using Windows (unfortunately), so c) doesn't apply.

For the most part, I'm getting the performance I need, so moving rendering to the GPU isn't absolutely necessary for me. My profiler says that most of the work is being done in qdrawhelper_p in some low-level math functions, so I don't think there's a higher level bottleneck. However, for a 1024x768 canvas, I'd like to be able to do 30 draws a second. Right now I can only get to ~20. (For smaller canvas, I have no problem with 30).