2) Spaces don´t work well with Lightroom. A nuisance; I´d liked to have one space reserved for LR full screen.[a href=\"index.php?act=findpost&pid=212541\"][{POST_SNAPBACK}][/a]
Lightroom was actually fine with Spaces until 10.5.2 (if I remember correctly) when Apple changed the way it worked and added a new option to the preferences. Since then, it no longer switches to the Lightroom space when selecting it, and if I then manually switch without selecting another program first, it ‘breaks’ spaces on my system until I log out and back in. (it doesn't let me bring up the all spaces view)
Just did a quick test on my machine comparing the speed, as I wasn't sure whether to be running in 64-bit mode or not. I'm running 10.5.4 on a 2.33GHz Core2Duo MacBook Pro with 4GB RAM, and tested by creating a new catalogue in Lightroom 1, Lightroom 2 in 32-bit and 64-bit modes and then importing 102 JPEGs (that have been edited) and rendering standard previews.
Lightroom 1, 32-bit—3:40
Lightroom 2, 32-bit—3:02
Lightroom 2, 64-bit—3:34
So it looks like you should only enable 64-bit if you are running with more than 4GB RAM in your computer even if you have a 64-bit processor etc. (it's what I expected, but I wasn't sure if that was the case or not)
Editing seems noticeably quicker in Lightroom 2 as well, though I haven't done any specific testing.
If Lightroom 2 is running slower, I would try optimising your catalogue to see if that helps.
Preferences > General Tab > Catalogue Settings > General Tab > Relaunch and Optimise.