Yeah, in school, I ran MacCAD on a dual-floppy SE. For simple 2D drawings, it worked fine. It didn't even attempt to do any 3d rendering, though.
For later classes with 3D rendering, we used IBM 386 PS/2s. Screen redraws of large drawings were painfully slow. We usually had our drawings in multiple 'layers', and turned off all that weren't absolutely necessary to the work we were doing right that instant. My senior year, the lab got one single 486. It was amazing. Incredible. Doing a screen redraw on a complex drawing only required 1 minute, instead of 10! (Today, even the most complex drawings we did back then would be so trivial, an iPhone could render it at many hundred frames per second.)
For later classes with 3D rendering, we used IBM 386 PS/2s. Screen redraws of large drawings were painfully slow. We usually had our drawings in multiple 'layers', and turned off all that weren't absolutely necessary to the work we were doing right that instant. My senior year, the lab got one single 486. It was amazing. Incredible. Doing a screen redraw on a complex drawing only required 1 minute, instead of 10! (Today, even the most complex drawings we did back then would be so trivial, an iPhone could render it at many hundred frames per second.)