I just installed iTunes 11, and I already want to uninstall it .. but don't know HOW.
I think it's clear that iTunes has become a vehicle to implement Apple's commercial goals more than OUR goals. So user friendliness is secondary to Apple's obsessive data-collecting habits. Our data.
How do I go back to my previous iTunes version?
I don't have the solution, but wanted to commiserate with someone with a similar issue. I have a similar iMac with the same RAM and am now up to OS X 10.8.3 with iTunes 11.0.2. I don't have an issue with iTunes under non-web-based operations, it plays music fine and syncs with devices without much problem. Where I have the problem similar to yours is when I am searching the iTunes Store.
Say I'm looking for a certain song. I do the search and click on "See All" for the songs on the results page showing everything that is sold. I could get a list of over a thousand versions or related songs. As I begin to scroll down this list with the added thumbnail of the album cover (in iTunes 11), I get to about item 100 and iTunes starts to bog down and get slower and slower. When I go to Activity Monitor to see what's going on iTunes is scooping up all the CPU and keeps chewing away at real and virtual memory. It gets slower and slower until it does become unusable as other have said. At this point it's taken up about 2 GB of real memory and an equal or larger portion of virtual memory and this is reflected over the rest of the computer and other apps (and I'm not running much else concurrently!) as all real memory is about gone. I never had this issue with iTunes 10, I never noticed any slow downs during many store searches. So do we have to put up with this super lag due to the album thumbnails? If so just give me the option to shut them off and search on a more responsive basis - as I am trying to buy something. I'm hoping future updates will get iTunes 11 in line.
I give you credit for waiting for iTunes to take its time to quit, as I usually give it the "Force Quit" and try again.
The same thing is happening to me on a Windows 7 machine. It scoops up all the memory and never finishes downloading new podcasts. I all can do is wait for it to go dormant, which it usually does so after 15 minutes, and then kill it, and then restart it so it will download one or two more podcasts.
This does not happen on two other systems I have that are both running Windows 7 but on multicore machines.