> Because how else do you explain this madness: they spent three years developing a new version of Racket that et the end turned slower than the original!

This is just a blatant misunderstanding of what Racket on Chez is trying to do, and a very limited understanding of what “optimization” means for something as complex as a compiler/interpreter. The point of the Chez backend is to improve maintainability and portability, not to increase speed [1]. Racket used to have a custom Scheme interpreter with a lot of custom C that was difficult to work with, so instead a lot of that code was ported to Chez - easier for everyone, especially Racket devs, even if it might take a while to smooth out some of the (very modest) performance hits.

And since you’re obviously totally ignorant as to why Racket decided to do all this work, it makes it hard to take your rant seriously.

[1] https://www.cs.utah.edu/plt/publications/icfp19-fddkmstz.pdf