Just for reference, here’s me cutting acrylic with a 1/4" single flute at 18k RPM, 140ipm
Using a three-flute 1/4" would have required to feed THREE TIMES FASTER to achieve the same chipload.
There’s just no real limit to how fast you can and should feed, in plastics (that’s also why you want to limit depth of cut to balance things out and avoid flute clogging)