guinea pig here ... no problems before, and no problems after.
I ran XBench and got a 1% performance drop on my rev. c PB 12". I don't use a rigorous set of test settings or anything, so this is within the margin of error probably, and of course should be taken as little more than suggestive, but the odd thing was the biggest change in any of the categories came in the "OpenGL Graphics Test," which was down 10% from where it was under 10.3.7. At the very least I make sure I have no other apps running when I do the test ... but was AP on or off, etc., who knows, whatever.
I ran XBench and got a 1% performance drop on my rev. c PB 12". I don't use a rigorous set of test settings or anything, so this is within the margin of error probably, and of course should be taken as little more than suggestive, but the odd thing was the biggest change in any of the categories came in the "OpenGL Graphics Test," which was down 10% from where it was under 10.3.7. At the very least I make sure I have no other apps running when I do the test ... but was AP on or off, etc., who knows, whatever.