If you use a slow hard drive , your BBS will appear slow. Get the fastest hard drive you can find!
You can make MUBBS a bit faster by running a memory cache. Then things like menus and "header" type files are always in RAM.
I have tried "Turbo Cache" with MUBBS and it works just fine. You need atleast 2 Megs when you run it and one line, get more memory for more lines! TURN OFF "WRITE DELAY" with it. TurboCash is a product by "PLI" and comes with their drives.
You could increase Apple's stock cache also. That seems to work too.