Python Import Performance - Module vs Function From Module

Question

Why does importing the entire module take less time than importing only one function?

%%timeit
import pid

269 ns ± 47.5 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

%%timeit
from pid import PidFile

1.77 µs ± 175 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)