From what I see, a four color PC color screen should be no extra color
especially if it's residing on workbench which I believe is the main reason
for the recomendation. I typically use an eight-color CGA screen and
haven't really had that much of a slowdown problem even on my one-meg
system. Sometimes I'll boot it down to 2 b-planes and let it pop over to
the Workbench screen or lower it's display priority or a combination for
speeding up the Amiga side. But by choice, I put the default to color.