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.