My hardware:

AMD X2 5400+
4GB RAM
Win7 64bit
GeForce 460GTX 1GB

Uber sampling and cinematic depth of field disabled => everything is as smooth as it gets.

Yeah I know what you mean. The only setting that really boost fps for me is lowering the resolution to 1280x800, but that means interpolation aka blurry mess!

I'm never a fan of gaming in a non native resolution the only game besides Witcher 2 was crysis 1, which was at 1280x800 otherwise I wasn't happy with the fps.

RIght now in the camp (prologue) everything is set to low+1280x800 fps is around 28-35fps which is playable but still it doesn't look right.

witcher.com forum is still not online.

I tinker a bit. Try lower your view distance. That's usually a killer. Go medium or something.
Light sources and AA are major FPS killer.

I use Macbook pro 2.2 i5. GT330M and 4Gb ram. Played on Low-Medium (custom) and 1280x800 and I played fine, though a little slow that I thought I would prefer.

Just turn off ubersampling. its what killed mine before. might be the same.

Strange. Even tho Nvidia drivers have SLi profile for The Witcher 2, I'm having a very poor performance with it. Can't even maintain 60fps with High settings (i7 @ 4GHz, 6Gb DDR3, 2xGTX 295)

I hope they release some fix for it.. ASAP.

Game runs really bad for me.
Turned down most settings in the launcher, doesn't help much.
Game feels unresponsive and laggy.


System:

Gigabyte P55 motherboard
i7 920
6gb ddr3
hd 4890 (updated drivers etc)
Vista 64

Everything's running pretty well for me. No slowdown, everything on besides uber and almost all settings high/ultra at native 1920x1080.
q6600 @ 2.4
8gb RAM (ddr2)
GTX 280
Win 7 64bit

According to notebookcheck.net, the 5870Mx2 is somewhere between a desktop 460 and 470. I have no idea how much a single 5870M compares unfortunately.

Tried the first 5 minutes of the games, didn't go quite far but with ULTRA (UberS off) :

E8500
4GB RAM (800MHz)
XFX GTX 260+ (latest drivers)
Win7 32b

Works quite well, still have to try big battles or towns (tonight since I'm stuck at job) but seems like everything will run fine... have some testing to do.

I'm not exactly pleased with the games performance either. Although it is quite beautiful on the "High" preset, I feel that my rig should run it on Ultra with no problems. It runs at about 20-25 FPS on Ultra which to me is unplayable.
My Rig:
Core-i7 2600k @ 4.2GHz
8GB of DDR3 Ram @ 2000MHz
2 Nvidia GTX 560 Ti 1GB in SLI

Don't get me wrong, it's gorgeous on the high preset. I think it just kinda stings that there's already a game that my month old $2800 PC can't play at the highest setting. I'm not convinced that it can't yet though. I think either the game or my cards need an update. I'm on the latest 270 Nvidia drivers though...

Very bad performance here too, Radeon 5970, disabling crossfire doesn't help, fps in the 20-30 range on *low*.

this is what i dont get, your getting that much fps with practically the same rig as mine..
im playing it windowed 1600x1050 now on medium and getting about 33fps with SSAO turned off.

http://pc.ign.com/articles/116/1168535p1.html Check this link for a fix for Nvidia users. It's at the bottom of the page. I have yet to try it but it looks promising.

UPDATE: I did this fix and it did the trick. I'm now playing on Ultra setting with only Ubersampling turned off and it runs super smooth. Technically I could play it with it on but I prefer the added performance rather than the better looks.