I have no idea how FORTH stacks up (haha) to other languages on modern machines insofar as speed is concerned. Modern FORTH is compiled so the difference may be

I have no idea how FORTH stacks up (haha) to other languages on modern machines insofar as speed is concerned. Modern FORTH is compiled so the difference may be quite less than the 3x you are proposing. On older machines, you will find published benchmarks showing FORTH to be 10 times slower than assembly. Compare this to BASIC which was usually 30-40 times slower than assembly in the best bases. I think your 3x speed difference between C and FORTH to be on the ball for these earlier machines. The other advantage of FORTH on these old microcomputers/microcontrollers is that threaded code tends to be quite compact, so you can write larger programs. Efficient use of memory was tantamount on old machines and controllers.