In short, the in-game frame limiter is busted and results in extremely uneven frame pacing, hence the stutter. We'll be using Nvidia Profile Inspector for this guide, so this solution is limited to Nvidia GPUs.

- Disable Vsync, FPS Cap and Screenspace Anti-Aliasing in the game's options. I recommend disabling Lockstep Mode as well. Your settings should look like this:

- Download Nvidia Profile Inspector[github.com], find the Divinity 2 profile, then set the following options:
Frame Limiter V3: 60 FPS (or your monitor's refresh rate)
Maximum Pre-Rendered Frames: 1
Triple Buffering: On
Vertical Sync: Fast Sync

(Optional, can be GPU intensive depending on your resolution/framerate)
Antialiasing - Compatibility (DX9): 0x000010C1 (just copy and paste this)
Antialiasing (MSAA) - Mode: Override any application setting
Antialiasing (MSAA) - Setting: 4x [4x Multisampling]
Antialiasing - Transparency Supersampling: 4x Sparse Grid Supersampling

Make sure to click "Apply changes" when done. Your settings should look like this:

While crashes aren't very common, they can still happen since this is a 32-bit application and it can run out of memory, especially during the Flames of Vengeance campaign. For this reason, applying the 4GB patch[ntcore.com] is highly recommended. The file you want to patch is bin\Divinity2.exe.