How to fix Dungeon Keeper mouse lag? A program to slow down CPU needed?
Solution 1:
Given that compatibility mode isn't work out, and you've some other issue with DOSbox, I'd recommend setting up a VirtualBox.
If you got an old Windows 98 (preferably) or 95 CD it's surprisingly easy to set one up.
One of the bonuses is the hardware virtualisation; you can set it to match the game's recommended spec (minimum 75MHz and 16MB RAM, ouch) to avoid some issues.
I've already done this to run X-Com Apocalypse, and it's as stable as it was first time round (at least it reboots faster now).