My game stutters at in-engine cutscenes seemingly whenever there's more than one model on-screen

I tried it with depth of field on an off and there's still lag,
I tried the game on low settings and there's still lag particularly when the castle appear onscreen
Compatability mode doesn't seem to work
setting the game to a single core doesn't seem to work

any suggestions?

The Depth of Field settings fixed this one for me... how does the game itself run? Is it faster than the cutscenes?

You could try forcing Vsync with the D3DOverrider program. Details in the big fixes post I made here:

http://www.gog.com/en/forum/the_witcher/fixes_to_common_problems

the game runs fine outside cutscenes

I tried forcing Vsynce with the D3DOverrider program and it still lags a bit
It seems to be the worst in the beginning cutscene (not the cinematic)

might have to just play it with small lag

that seems likely, after the intro the game only stutters when loading in a big enemy/landscape. Might just need to clean up my PC