From Gambit wiki
Marc Feeley has collected together a collection of benchmarks, called the Gambit benchmarks; the performance of Gambit is compared to a number of other scheme implementations on that page.
The "Programming Language Shootout" benchmarks
The Computer Language Benchmarks Game proposes comparing various computer languages by benchmarking similar algorithms to a number of small problems in various language implementations. I've started a programming language shootout benchmarks page that contains some of these programs implemented for Gambit. Please feel free to propose improvements before they're submitted.