Hi folks,
Here's how I solved the iCloud CPU hogging issue.
Like most I quickly found that the bird and cloudd processes lookup
1. Unplugged from network/internet.
2. Killed both cloudd and bird, (you can do this via command line by using TOP to find the process id {PID} and then KILL -9 {PID} or the Activity Monitor and force quit)
3. Undo any setting that forces your disk to securely delete file or securely empty trash. In my case I had this on by default and had recently trashed files from the iCloud folder. I'm not sure if this was the root cause but it's something I did in the process of eliminating anything that could have restrictions on the iCloud files and folders.
4. Empty the trash. Make sure that non of the iCloud files were open or locked by other application/network/etc.
5. Restarted iCloud service. Thanks to Sorki, ran "brctl log --wait --shorten"
6. Wait for all files to sync. Gotta be patient. If it's the first time you put large files or large quantity of files, you gotta give it time to sync.
7. Been running fine for days.
I have 3 computers that are all tied to iCloud. All are now working great. Only my iMac 2010 had the slowdown. Judging by the fact that only one had the issue I knew that it must be a local settings issue, a large file, or some sort of file system restriction.
Hope this helps.