This from a poster on Digg
Intel Core 2 Duo e6300 @3.2 Ghz
2GB of DDR2-800 @1066
Geforce 7900GS OC'd @ 600/1600
2X 320GB Seagate .10 + 1x 500 Seagate .10
It doesn't run very well at all, it's playable, but it does give some lag when hitting the keys. My system can play COD4, Bioshock, and Dirt @1280x720 very nicely, but Guitar Hero lags. Hopefully you guys don't get as popsnizzlety as a port as we got.
...Overall, the PC version of Guitar Hero III is a solid port of a fairly awesome game. If not for the high system demands and random slowdowns, it might actually compete with the 360 and Wii for the best version available
This video from an angry youtuber entitled "Guitar Hero 3 for PC SUCKS" outlines this most obvious problem with GH3. At around 1:00 in there are several Lag Fits which result in the player missing notes. The youtuber, "Bakudai" comments that "everyone who worked on it(the PC port) should seriously think about killing themselves.". Youtube has seemed to have become a small vehicle for users to vent their thoughts concerning the game. These comments come from a test video of GH3
Game spot mentions these points in its PC review
...One thing about the PC version of Guitar Hero III that makes it potentially more difficult than its console brethren is the generally slothful performance the game can turn in. The steep minimum system requirements include a 2.8 GHz dual-core processor, a gig of RAM (2 gigs if you're running Vista), and either a Radeon X800 or Geforce 7600 video card to run. On the two systems we tested, which both exceeded these statistics, we still ran into some general sluggishness with the game. The 360 and PS3 versions of Guitar Hero III had some notable frame rate issues, but nothing quite like this. Notes will sometimes seem to be behind the music, and it's not uncommon to see notes just skip on down the fretboard to catch back up. For a rhythm game this is a killer, since precise timing is needed for success. The Vista machine we tested on displayed issues like this only on a very infrequent basis, and with a bit of lag calibration, it mostly ran quite well. However, the XP machine we used (which included a Pentium D 3.40 GHz dual-core processor, a gig of RAM, and a Geforce 7800 GTX video card) became practically unplayable in spots, even with all the graphical effects turned to low and the crowd graphics turned off.
So far i have heard no comments on the mac port.
Another interesting point i noted down is that there is supposedly a lot of In-Game advertising that didnt seem to find its way to the Console versions one reviewer said he hoped these adds didnt come at the expense of performance.
I am looking foreward to seeing how performance turns out on Mac OS X, and i bloody hope Aspyr (for their sake) fixes these performance issues.
P.S i hope more that the hybrid version hits Aussie stores verry soon