That's pretty specious. You can easily write a function defined inside a function that you can pass by just naming it. "Anonymous" functions are just syntactic sugar. Furthermore, writing a new python named function is easier (fewer chars) to write than a javascript anonymous function, so the "sugar" gained is moot.
Finally, as you build more and bigger systems, you realize that those multi-line anonymous functions you had you actually want to be named (for documentation) and tested. So you'll end up de-anonymizing the complex (multi-line) ones anyway.
As for speed, why not compare a jit (v8) to a jit (pypy) ?
