Reducing the size of iTunes art saves quite a bit of memory
Of 486 CDs ripped to iTunes (nearly 8,100 songs) about 3/4 have art that I've either sourced via Google or (for about 50 albums) had to scan. Although I limited my scans to 500 x 500, with the Google-sourced art, for ages I wasn't keeping a tab on the size of the artwork I was downloading (though I doubt if much of it was more than 1500x1500), nor am I sure how large the iTunes-sourced artwork is.
Anyhow I found an iTunes script on the 'net last night which hacks-down the dimensions of your iTunes artwork to a maximum size you specify. You have to do it in batches of less than say 800 songs each, otherwise both it and iTunes throw a fit, but even with that constraint I'd finished in about 45 mins.
Specifying a maximum of 500 pixels, It's amazing how much free space it liberated: over half a gigabyte, which is probably enough for a 74min CD ripped as ALAC, or quite a bit more than that if you rip as AAC or MP3.
So another tip I've learned is "control the size of your iTunes art: it's amazing how much memory it guzzles".