Javascript engines are fairly speedy compared to CPython; not only are they industrial-grade JITs (as opposed to CPython being a naive interpreter), but JS is an easier language to optimize. Further, WebAssembly has overhead.
The CPython interpreter has actually seen a lot of performance work, they've long been pushing the boundaries of interpreter optimizations that you can do portably & compatibly. I wouldn't describe it as a "naive interpreter".
5-7x difference seems reasonable to me.