Comment by NelsonMinar

I agree Python's startup time is too slow. But one trick you can use to improve it some is the "-S" flag, which skips site-specific customizations. On my Ubuntu system it brings Python 3.6 startup time down from 36ms to 18ms for me; still not great, but it helps.

The drawback is this may screw up your Python environment, not sure how easy it is to work around it if it does.