So far P7 has run with far greater stability on my machine than P6 or P5 ever did. Not a single crash, freeze or burp in over a week's worth of heavy use, although admittedly there are still some features I haven't stretch-tested yet. My main machine is a Mac Pro 2 x 2.66 GHz Dual Core with 4 GB of RAM. P7 is notably faster in every respect except loading figures, where it is slightly slower. Renders are MUCH faster, as is movie-making (natch). As someone else said, P7 seems to love the Mac OS. And the multiple-undo is so sweet sometimes I do it just to prove I can.