Part of the issue is that because Python is so dynamic lot of lookups have to be done to do something as simple as a function call. Tight loops of arithmetic (f

Part of the issue is that because Python is so dynamic lot of lookups have to be done to do something as simple as a function call. Tight loops of arithmetic (for example) in Python are actually fairly fast, but if you call a function it has to do a load of work to work out what code you actually want to run. It might have to: Look up which object the method belongs to, look up the namespace, check if there's an implementation of __getattr__ or equivalent, maybe call that, get the result and then actually call the function. More complicated cases get worse. Erlang/Elixir are much simpler and get their flexibility from functional programming. There's much less indirection so less work the interpreter needs to do.