I have Mint 12 running on an older AMD64 3700+ and it is running GREAT out of the box, I haven't even fine tuned it or tweaked any config files yet!
Precise 12.04 was slow on that box, (Lubuntu) very CPU intensive, idled at about 70 and jumped up close to 100% when taking a screenshot for example and had a lot of bugs, hangs etc.
I have Fedopra 16 , and openSUSE 12.1, MacPup528, and Puppy (wary) all on it on different partitions, (and still an install of 10.10 Maverick) (and a couple more;)
but the Mint is the fastest besides maybe the Wary Puppy, and Maverick so far, and it seems really Stable so Far.
Fedora is pretty fast with LXDE, but has locked up twice and SUSE gets unstable after a while it seems, (all before I tweaked them, and afterwards), but Mint has been on a while now and is rock solid so far, and it may win out in speed overall too even, as I haven't even fine tuned it yet, still using defaults, (Gnome), will tweak it tomorrow.
I am thinking of partitioning me some more Mint space now...
If nothing adverse happens it looks like I will be using Mint on my laptop and other box too, Since Support ended for Maverick.
I tried KDE in SUSE and Gnome 3x. I settled on Gnome and manually configured it till I got icons on desktop etc, and some menus on there too, was a task, but Mint has the Best of both worlds already!
I am Loving Mint 12, Thanks!!!