It depends which software you use for viewing VCDs. MediaPlayer is usually slower, I prefer using software like PowerDVD.
I'd say 75Mhz is really a bit slow but I'm sure there is also a VCD-Viewer for DOS. You could then shut down windows to the dos-shell and view from there.
I don't know where to find a dos viewer but you can take a look at http://www.vcdhelp.com.