I noticed the fans in my Macbook Pro were running excessively. When looking at Activity Monitor, I noted that the Dock was using 100% of the CPU. A quick search on Google, and I found the culprit to be Parallels. The root cause is an issue with the graphics API between OS X 10.6.8 and Parallels Desktop 6. I had indeed recently updated to 10.6.8 in preparation for Lion.
The details can be found in this Parallels KB article:
Mac Dock consuming 100% of CPU core after upgrade to Mac OS X 10.6.8
Symptoms: Dock consumes 100% of CPU
Environment: Mac OS X 10.6.8, Parallels 6.0.12090
The Solution Rather than downloading from the web site, I simply ran the “Check for Updates” on the Parallels application menu.
