Obviously the author wanted to quote the slowest plotter of Drawfiles (the Viewfinder) so his speedup code looked extra quick?
If he had quoted the speedup over the Iyonix, would ppl bother talking about it?
Many years ago the authors of ImageFS showed at a Acorn Show their code for plotting lines to the screen very fast. It could do transparency, sprites, clipping and realtime moving of objects without the usual 'outline' shape on a humble RiscPC.
I was gobsmacked when I saw it.
Was anyone interested in putting this into RISC OS? No.
Are they in this market any more? No.