I remember back when I had a bunch of Pentium II/III systems set up on a network, I had this win9x-based utility installed on some of them that allowed you to throttle the CPU speed in DOS applications through a GUI, and as far as I remember it added an extra tab to the "properties" dialogue whenever you right clicked on a DOS program or PIF file.

I remember it was quite effective for running Warcraft II (even on a 1GHz Pentium III!), and unlike most other programs of its type it would only kick in whenever you loaded a DOS application, so you didn't have to worry about it slowing Windows down to a crawl. 😁

As well, I also remember it loading as a Windows startup item, and it offered percentage-based speed throttling (50% was good on a Pentium II or lower-end Pentium III, 25% was good for the 1GHz box, just to give you an idea).

I would love to find this program again, and before anyone asks I remember it being freeware, so it's not like I'm looking for warez. 🤣

EDIT: Wait, I think I've found it! 😁 http://www.csclub.uwaterloo.ca:11068/myslow/