ITunes 11 CPU keeps peaking at 100%

Question

Most operations in iTunes are resulting in CPU peaks of 100%. This makes iTunes agonisingly slow to use. Can anyone suggest any adjustments to make it less CPU-hungry?

Answer 1

I was having the same problem.  I have a brand new Macbook Pro Retina 15" 2.4GHz i7. I called support 3 times to try and work it out.  We tried re-installing iTunes and a host of other things. It came down to there being a problem with the library.  I had imported it from an earlier version of iTunes from an older mac  (Where it worked fine.)  In the end I just had to re-load all my songs into the library.  This is no small feat as I have around 185K songs in over 1TB in my music library. 
The problems i was having were-
-sluggish performance, gap between song playback, slow searching, slow quitting (Or not quitting at all until a force quit)  It was essentially unusable
-using 100% or more of CPU.
-not being able to remove songs from the library.
- having multiple temp files appearing in the music library folder
I ended up creating a new library in the music folder in the sidebar. (Its default location).   I keep my files on an external HD, and set up the prefs to keep the music folder there.  You will want to export your playlists somewhere where you can find them and import them after you build the new library.  As long as your files don't move, iTunes should be able to load everything back into the playlists.
   Once everything was set I went to iTunes/Files/Add to Library and manually selected a chunk of my library, then let it process.  I would take a letter or 2  at a time so I could redo if necessary.  (such as bands starting with" A", starting with "B" etc).  normally it would take 3-4 hours per letter.  I would let it do its thing, then quit and restart itunes, make sure it was playing, quitting etc as it should.  It took me 4 days to get the entire library re-entered, then re-loaded my playlists, and now it seems to be working just fine. 
Obviously this was a pain as it took 4 days to re-do, but there was something about the old library that itunes just couldn't digest.  Now itunes runs at around 2% CPU when playing, maybe 20% when searching etc.  it will quickly play another selection when chosen.  just like it is supposed to. 
it's the slow way to fix it, but it was the only thing that has worked for me.  I finished this 2 days ago, so time will tell if the problem crops up again, but for now averything seems cool.