I use PeterK's icon.library on a 68060 and CV 64 A4000 with Kens PNG icons. Any slow down if its there is neglible.
TBH its all eye candy anyway. The icon is supposed to be a pictorial representation of the file- you are supposed to know what it is without looking at its name. I find I rarely do that, and the icon is nothing more than the place I click- which I could do just as well in 4 colors, maybe even better.
