Wow, I remember this! As a kid, I remember taking my computer to an IT shop asking how to run a copy of Ultima VI on my Pentium II MMX PC. The tech there had it for a week, and they figured it out by setting up autoexec.bat so that I had to allow/disallow some processes from booting one by one.

Apparently one of those tricks was reducing the amount of available memory, or something like that. That was the hack that got U6 to boot and be playable at a normal speed.

This would have been in 1998 or so, so my memories of the exact fix are pretty faint.