I am a little skeptical as well, but I do think there is a lot of areas for improvement beyond the changes going in mainline. Note that while Mojo intends to su

I am a little skeptical as well, but I do think there is a lot of areas for improvement beyond the changes going in mainline. Note that while Mojo intends to support all of python, they never claimed that it will still be fast if you make heavy use of all the dynamic features. The real limiting factors are how often those dynamic features are used, and how frequently the code needs to be checking whether they are used. The fast CPython changes are still very much interpreter-centric, and are checking whether assumptions have changed on every small operation. It seems to me that if you are able to JIT large chunks of code, and then push all the JIT invalidation checks into the dynamic features that break your assumptions rather than in the happy path that is using the assumptions, you ought to be able to get much closer to to Javascript levels of performance when dynamic features aren't being used. Then support for those dynamic features becomes a fallback way of having a huge ecosystem from day one, even if it is only modestly faster than CPython.