I'm not sure if this is the right spot, but it seams the closest, as far as I can tell.

I have the game from GOG, and it's installed at C:\GOG\Kings Quest 8 on my PC running Windows 10. When I play the game, and it plays smoothly, if I save or go to the menu screen for any reason, it crashes and I have to reopen the game all over again, which is a pain on puzzles that it's pertinent to save constantly, such as the 2 story tower in the Swamp. Is there a way I can fix this?

Edit: I was messing with the game options and noticed it only does this in DirectDraw. If I put it in 3Dfx it doesn't do this but runs unbearably slow (where it takes a good 30 seconds to fully turn around if a baddy is behind Connor)

First thing to do is contact GOG to see what they have to say. They can be unbearably slow, so be patient. I would check for you, but it's midnight here and I'm heading to bed. Check the forums at GOG for this game and see if anyone else is having this problem.

I don't know if this would help you or not, but I have the game installed on my Windows 7 computer with the patch that I downloaded from here and the game is running well. I found this patch via the GOG forum and it supports Windows 10 as well as the GOG version of the game.

I wanted to pop in and say I did finally get a reply on GOG's forum, but what Nicode told me to do didn't change anything, BUT while playing last night, I found a workaround with the crashing after saving. When you save, if instead of resuming game, if you click load game and load the save you just made, it plays just as well :D:D