I agree completely with your anecdotal experience. It has been my experience as well.
However, I'm quite sure that the speed difference we've observed here is not due to the language implementations at the interpreter level. The two languages are similar in performance in that respect (Python being maybe incrementally faster, but not enough to notice most of the time). The faster speed noticed in this anecdote has got to be almost entirely due to the superior efficiency of the code in the tools we're using. Bundle is just slow basically.
However, I'm quite sure that the speed difference we've observed here is not due to the language implementations at the interpreter level. The two languages are similar in performance in that respect (Python being maybe incrementally faster, but not enough to notice most of the time). The faster speed noticed in this anecdote has got to be almost entirely due to the superior efficiency of the code in the tools we're using. Bundle is just slow basically.