As I said yesterday, I hereby post this excellent workaround I found on another forum that discussed the same problem with a DDraw based game.

1: Go to the DirectX Settings. Appears to be hidden in Windows8, download this cpl component shortcut: directx.cpl
2: Make sure you open this applet with admin rights, proceed if you have.
3: Go to the DirectDraw tab and untick the checkbox Use Hardware Acceleration.
4: Make sure you do this on DirectDraw only, as disabling hardware accel on Direct3D will likely break modern games. Just don't casually tick anything else.
5: Press OK to apply settings. If you have JJ2 open, restart it to take effect.

It should be noted that this will come with a strange side effect. It pushes the fullscreen FPS to 120 while normally that would've been 70. It'll make screen movement slightly more wobbly somehow, but at least it plays lots and lots better than the 30 FPS you're otherwise stuck with on Windows 8.

And to clarify for those interested to look further into the problem, it's proven with several setups (by me and other folks) that this Win8/DDraw bug only happens while using DDraw with either double or triple buffering, but not with a single buffer. Even though JJ2 has a -notriple flag, it'll make no difference as it apparently just double buffers instead.