> White space significant, good luck minifying it.
Brython supports precompilation to JS, which is obviously minifiable.
> on top of that you are running Python interpreter in the JS VM.
No, you aren't. Brython is not a Python interpreter, but a compiler to JS. There are optimization issues from the need to maintain Python semantics interfering with optimizing the JS, but that's not the same as running a Python interpreter.
Brython supports precompilation to JS, which is obviously minifiable.
> on top of that you are running Python interpreter in the JS VM.
No, you aren't. Brython is not a Python interpreter, but a compiler to JS. There are optimization issues from the need to maintain Python semantics interfering with optimizing the JS, but that's not the same as running a Python interpreter.