The PyPy website suggests this is the case.

https://www.pypy.org/features.html

> Our main executable comes with a Just-in-Time compiler. It is really fast in running most benchmarks—including very large and complicated Python applications, not just 10-liners.

> There are two cases that you should be aware where PyPy will not be able to speed up your code:

> Short-running processes: if it doesn't run for at least a few seconds, then the JIT compiler won't have enough time to warm up.

> If all the time is spent in run-time libraries (i.e. in C functions), and not actually running Python code, the JIT compiler will not help.