[sabauma]

Chez is pretty tough to compete with in terms of Scheme performance. On the benchmarks presented in the paper, Chez averages faster than all the systems presented, even Pycket post warmup. Its not the fastest on every benchmark, but gives consistently good performance without huge warmup time, which is Pycket's biggest weakness. With Racket planning to switch over to Chez, it may be difficult to justify Pycket's existence, especially if some of Chez's known performance sore spots receive attention.

[throwaway7645]

Is Chez AOT compiled or JIT based? If it is AOT, would the REPL still be interpreted and just a finished program AOT compiled?

[sabauma]

Chez is an AOT compiler. I am not sure how the REPL operates, but I believe it just compiles expression on the fly before executing them. I suppose you could characterize that as JIT compilation, but the optimizer does not make use of any runtime profiling information. Racket's "JIT" is similar in that code is generated for a function when it is first called, but the optimizer is run on the bytecodes of the program before anything is run.