Anybody else experiencing this?

As expected changing the resolution etc. didn't change anything, neither did compability mode help resolve this issue.

Try turning off post processing and see if that helps.

Turned everything off or to low, sadly it changed nothing. Weird thing is the Steam version runs just fine.

On Steam with High settings the game runs with about 35 FPS.
But the GOG-version on the lowest possible settings runs only on 22 FPS.

Having this same problem, performance is horrid...

I have an Nvidia graphics card (GTX 1060) and I'm on Windows 10.
I thought Windows 10 is the culprit of the framerate issue, but I gave it a try and installed the Steam version again and for some weird reason it runs smoothly. :/

Ah. I've found out something, but may not be very helpful - GOG's GOTY edition of SRIV has a few extra graphics options that seem to default to on, post-processing stuff and such...

Sorry for necro on a 6 year old thread, but this is one of the top google results for the issue and I found a definitive solution for this. Also the audio desync, and it applies to SR3 as well. At least for nVidia, but may be possible on AMD too.

Setting a framerate cap -- ANY cap, as long as it's not absurdly high -- in nVidia control panel solves all the issues SR3 and SR4 have. Even if you aren't hitting the cap before you hit your vsync target. For example, I run the game vsynced to 60fps, but setting a 150fps cap in NVCP totally resolves the issues even though the game never actually hits that framerate, and runs comfortably at the 60fps vsync target.

I suspect something under the hood on the CPU side of things is spinning to the moon and causing issues, and setting a hard framerate cap on the game prevents whatever it is on the CPU side running too fast for its own good.

Do note that cutscenes are hard capped to 30fps for animation keyframing reasons, but now they'll actually hit that target.