To mirror asguy's comment, this only tells us about the performance of this particular FORTH engine, it doesn't tell us about the performance inherit to FORTH (which of course doesn't exist, it's down to the engine).
Whether anyone has made a sophisticated optimising FORTH for 6502, I don't know.
>this only tells us about the performance of this particular FORTH engine
Yes, exactly. Whatever its other qualities may be, I suspect this particular Forth has overlooked some pretty obvious low hanging fruit, performance-wise. In this[1] post we learn that LOOP puts a 1 on the stack then falls into +LOOP. Although there's elegance (and a memory saving) to that approach, I'm startled that they didn't provide a dedicated definition for LOOP instead. AIUI, implementing LOOP as an instance of +LOOP substantially and needlessly increases the complexity of what gets executed. Yes, I know premature optimization should be viewed with suspicion, but if profiling were performed it's hard to believe LOOP wouldn't be a hot spot! So, I constructively suggest that in this respect at least (and perhaps there are others) this Forth engine could benefit from some tuning up.
