Peter Chamberlain said they have not come across any problems yet with 10.8.3, so I updated (and CUDA 5.0.45). My Resolve performance seems unchanged, but I have been noticing weird problems in Safari and FIrefox. Sometimes choppy playback of Youtube videos, and sometimes horizontal tearing when scrolling quickly. But not always. Neither Nvidia nor Apple will help of course, since the GTX5xx series is not officially supported. Rats. This is life on the cutting edge.