You can time code with Python’s built-in timeit module:
from abjad import *
import timeit
timer = timeit.Timer('Note(0, (1, 4))', 'from __main__ import Note')
print timer.timeit(1000)
0.225436925888
These results show that 1000 notes take 0.23 seconds to create.
Other Python timing modules are available for download on the public Internet.