So I don't have the greatest PC ever, but it is certainly well beyond what this game requires. Despite that, I have to turn all of the graphical settings down to their absolute lowest, run at the lowest possible resolution and turn off the audio effects, just to get enough framerate out of the game to move my character around. Even with that, the game is still unplayable, since as soon as any other action appears on the screen, the framerate tanks completely. This is with a fresh download and install of the game, current drivers and current DX. System specs:

Windows XP SP3
Intel P4 3.0GHz w/ HT
3.0 GB RAM
256 MB GeForce 7600 GS
SoundMAX Audio (on board/integrated sound)*
Widescreen monitor (game performance the same using either widescreen or 4:3 resolutions)

Note that I did cancel the PhysX install for the game, since I already have a newer version installed. Also, running the game in "safe mode" (windowed 640X480) does seem to work OK... but I shouldn't have to run the game in a tiny window just to play it.

Thanks in advance for any help.

EDIT
*I have since replaced the on-board sound with an Audigy LS I had lying around. Zero difference in game performance.

I just completed a full reformat/reinstall of Windows (not for the sake of this game, it just needed to be done). All I had installed were all of the Windows updates, the latest version of my hardware drivers and the latest DirectX. I installed the game and it doesn't work any better, so I think I can now be certain that the performance issues have nothing to do with any software that might have been on my machine, which leaves me with hardware and the game itself. I tried the affinity toggle trick Mothra suggested and it didn't seem to do anything more than the simple ALT-TAB trick already was doing.

I have to turn down the res too, I doubt there's anything else you can do short of buying a better computer. =P

Check out the free program called Game Booster. It helps sometimes, but I had to turn down the graphics on this game even with it.

I used to use Game Booster, but I never really found that it did all that much for my performance and often left the system quite unstable. I would get a better computer, if it weren't for the expense of it, plus there is really no reason I can't get better performance from this game on the hardware I already have; it should be more than enough to run this game well.

I find it noticeably improves some games, just not all. If it left your system unstable, you should reinstall it and take a look at the list of programs it is set to close. If there are important ones with a check next to them, uncheck them and you'll be more stable. If there are unimportant ones without a check next to them, check them off and you'll notice more of a performance increase. Also, maybe you used an early version.

I'm also getting horrible performance from this game. Can anyone share some tweaks to make the game run better?

I have a similar specced PC to the OP, and it runs terrible on my rig too and crashes after about 5 mins of play time. I know this game is capable of running on my machine because when the demo first came out those few years ago, I could run it fine with no problems and my hardware has remained pretty much unchanged since. In its present state though it is unplayable for me.

Oh yeah I should also add that the sound in the cut scenes is stuttery for me and that the spoken dialogue keeps cutting to the next character a few words before they're due to finish their sentence. I did try that fix some one supplied for the missing NPC dialogue but that didn't affect my problem.

My setup was similar to the OP :

XP SP3
P4 3.2
2.0 GB RAM
256 MB 7800 GTX
Realtek onboard sound

Apart from an occasional stutter, the GOG version played well and was stable - in 70+ hours of play it crashed maybe 4 times.

- overclocking can cause problems in some games.

- do you monitor the temperature of your video card during play ?

- some combinations of hardware (especially mobo / video card) can be troublesome

- if you're running an Intel chip, check to see if there is a BIOS update for your motherboard. The board I was using had something like *14* updates over its lifetime (which is why I've gone back to AMD in my current PC)

I played a non GOG version of this game some years ago with older hardware and I remember it running okay. Maybe the GOG version of Two Worlds not only has the lip sync problem but also runs slower? It is probably just my imagination.

It appears I may have (finally) found a solution to this problem that works for me. The system I am running this is an older system with an AGP graphics card and I happened to notice while messing with my BIOS for a completely unrelated issue that I had the AGP aperture size set to a lowly 32 MB. I upped it to 128 MB and now the game runs nearly flawlessly.

i'm having this problem also, kind of annoying to read really fast and still risk missing an important piece of information... any ideas?