On the trinket m0, have a file "mylib.py" (attached sample) with 14 functions and 2 class definitions.

In REPL, call:

import time
var1= time.monotonic(); import mylib; print(time.monotonic()-var1)

This takes about 14.7 seconds on circuitpython 3.0, and 0.1 seconds on 2.3.1

mylib.txt