Hm yeah I see what you mean. I don't know the details of how v8 deals with __proto__, but I can see in theory they are similar. Though I think the general poi

Hm yeah I see what you mean. I don't know the details of how v8 deals with __proto__, but I can see in theory they are similar. Though I think the general point that Python is a very large language does have a lot to do with its speed / optimizability. v8 is just a really huge codebase relative to the size of the language, and doing the same for Python would be a correspondingly larger amount of effort. I don't know the details but v8 looks like it has several interpreters and compilers within it, and is around 1M lines of non-test code by my count! v8 was written in the ES3 era. And I knew ES3 pretty well and Python 2.5-2.7 very well, which was contemporary. I'd guess at a minimum Python back then was a 2x bigger language, could be even 4x or more.