Me Too - and Thanks
I just finally got around to upgrading to Yosemite on my MacBook Pro and my CPU temp spiked (as monitored by iStat).
After a day of digging, finding this post, and realizing that the "Folder Items Dispatcher" was not similar to the Windows "System Idle Process" disabling the Folder Actions cured by CPU high heat problem.
I upgraded a second MacBook Air at the same time and it had no CPU problems BUT the Folder Actions check box was unchecked at the point of the upgrade. Just for fun I checked it on the Air and Activity Monitor showed the Folder Item Dispatcher at nearly zero CPU. I rechecked it on my MacBook Pro, the pinwheel started, and the CPU spiked for about 30 seconds, and now it is back to normal.
I have an aftermarket SSD in my Early 2011 MacBook Pro. About 7 months ago I upgraded my older aftermarket SSD to a larger one using SuperDuper!. At that point I was experiencing very high CPU use. That problem was caused by some old cache files that needed to be rebuilt with this terminal command:
sudo update_dyld_shared_cache -force
Tech Support from Shirt-Pocket Software (author of SuperDuper!) were great. I struggled for several days and considered removing the SSD, which was a different brand. I finally sent a tech support request to Shirt-Pocket to ask if something could have happened during the disk cloning and in just a few minutes they said "Try This". Bingo and fixed.
It seems now that my VMWare Fusion is eating a little extra CPU because of a Windows process but this one seems manageable and maybe even a Windows issue.
Thanks.