People complaining about driver problems tend to talk about more subtle problems than "performance".
Performance is nice but smooth and correct operation is more important to me so when I complain it's usually related to odd behaviour that I didn't observe with the blob.
Originally Posted by bridgman
Most of the cases I have seen where performance is really bad are related to install issues more than fundamental driver problems, although I'm sure there are exceptions to that. If you install a new fglrx driver on top of an existing one without uninstalling the existing driver first you can get some really tough-to-debug problems.
Just as a common sense precaution which is backed up by your commonly provided advice to always un-install an old version before installing a new one that's what I've always done. I used to do this with the earlier nV blobs as well but got lazy and found it wasn't necessary there. Just to be sure when moving from 10.5 to 10.6, 7 and 8 I've done that. I'll be doing a fresh install and testing with that when 10.9 is rolled out which might coincide with Ubuntu 10.10.