I doubt any dynamic language implementation on top of .NET could ever compete performance-wise with one of the modern JS engines. The CLR doesn't allow for cert

I doubt any dynamic language implementation on top of .NET could ever compete performance-wise with one of the modern JS engines. The CLR doesn't allow for certain low-level implementation tricks, like tagging pointers, and doesn't give you full control over the memory layout of your data structures. Also, all code generation has to go through the .NET JIT and the .NET runtime code generation APIs, which both aren't really optimized for the use by dynamic language runtimes. However, Mono might be a better platform for dynamic languages, because the Mono team might be open to extending the core with some specialized infrastructure for dynamic languages...