Oh! Slimmed! I kept reading that wondering whether System 6 had anything to do with Ghostbusters.

I did a lot of slimming back in the day of 7.5.5 and 7.6.1, but there was a lot more to slim.

If you're running only on classic m68000 machines, then you can use ResEdit to take out all icon and pict resources with more than one bit of color.