Hmm, lots of anecdotes and complaining here. I've experienced no issues of the sort. Running perfectly smoothly here on 12.04, 64-bit. And I'm on a 4-year-old Pentium Dual Core machine, of all things.
I did not read through all of the posts, but it appears to be related to nVidia hardware. I'm guessing that you are not using an nVidia card.
On a side note, I gave up nVidia hardware altogether (about 4 years ago) because of endless issues with Linux (and macs). This thread isn't encouraging.
Same here, but with an even older computer: AMD 64 4000+ with compiz turned off and running LXDE on the desktop. No issues so far and I haven't had any crashes at all.
