And for those saying that Aperture etc is running slowly, I found that Spotlight wanted to index in the background for hours on end after upgrading but that switching it off then on again several times cured it.
Anytime things seem slower than they should, check Activity Monitor - likely something is hogging your cores. Personally, I have iStat showing CPU activity in the menu bar, so I can notice that happening before things get slow or the fans kick to high speed.
Aperture seems slow and it's the one using up everything there is. Preview does the same thing when browsing RAW photos.Close to 400% in processor usage... What ever that is supposed to mean.
EOS 5D Mark III
8-15L, 24L II, 85L II, 100L + a 35mm Sigma