In my experience Pico-8 maxes out at something kinda-sorta approximating 4MHz, although in the words of the author, "PICO-8 CPU costs are made up and essentially silly when looked at too closely."[1]

The CPU in the Playdate prototype runs at 216MHz.[2] The numbers aren't directly comparable, but I'd wager that the Playdate will have _significantly_ more headroom.

1. https://www.lexaloffle.com/bbs/?tid=33883

2. https://twitter.com/zhuowei/status/1132447884719210497