Statically compiling dynamically-typed Python to statically-typed WebAssembly would be similar to how Nuitka [0] compiles Python to C. This compiled code may be a little faster than interpreted Python, but it's still going to be quite slow - much slower in a browser than JIT-compiled JavaScript.

AFAIK the ideal way to maximize the performance of Python in the browser would be to JIT-compile Python code to WebAssembly. Does anyone know whether WebAssembly implementations are able to support that?

[0] http://nuitka.net/