E.g. javascript can have thousands of subpackages/dependencies and it starts up instantly. Scipy is huge but importing it is practically instant. "Classic" AOT can take ages to compile, but it doesn't have to compile on every run.

JS does this by multi-phase JIT. Python by being dog slow in the execution and AOT by being dog slow in the compilation.

I think Julia's "JIT-AOT" may be a good approach (and perhaps almost necessary for Julia's dispatch) too but it seems to be very hard to make start up fast.