The game runs just fine if I'm doing nothing. If I move, the game becomes choppy, almost like a slideshow.

I ran NWN2 without problems a few years ago, but I've since upgraded to Windows 10. I tried running in Compatibility Mode for Windows XP service pack 2, no luck.

Apart from the operating system change, the only real difference between now and then are probably driver updates.

Might there be a fix? I was hoping to play through the campaign with my brother.

EDIT: Did some searching, found a fix: The "Client Extension" mod which I found on the Neverwinter Vault website.

I copy-pasted the folder's contents to my NWN2 folder, ran NWLauncher, and the game works without a hitch now.