vgatherps parent
Outside cases where Python is used as a thin wrapper around some C library (simple networking code, numpy, etc) 10x is frankly quite conservative. Depending on the problem space and how aggressively you optimize, it's easily multiple orders of magnitude.
Those cases are about 95% of scientific programming.
This is the first line in most scientific code:
import numpyFFI into lean C isn't some perf panacea either, beyond the overhead you're also depriving yourself of interprocedural optimization and other Good Things from the native space.