Try XP compatibility mode?. I mean, the game is clearly a 32-bit / DX9 one or I couldn't play it / Try 334.89 drivers? =
No (portrait / invertory) freezes or audio delays, even though my CPU & GPU are a little bit, below the minimum. But only "a little bit":
GOG version / Win XP SP3 (optimized for audio recording) / 2 GB (of DDR 400) RAM / Nvidia GT520 (Drivers: 334.89) / 1280x720 (windowed) / and .. .....wait for it........ AMD Athlon 64 3500+. "Suprise suprise" - it runs kinda (or really really) badly, but it actually r-u-n-s. You know - the opposite of not running or constanly freezing?.
"Zoom in" (like at the tree with the hanged people in Gilded Vale) & "sneak around a lot" & "use middle mouse button to move to screen, instead scrolling it with arrow keys" fix screen lag & SPF instead or FPS problems. My game clearly has this "memory bleeds out and when you try to leave an area and to go the next, it crashes as there's not enough memory left" issue. But "Save. Quit the game. Start the game. Load" has worked ev'rytime.