benchmark-run is an autoloaded Lisp macro in `benchmark.el'.

(benchmark-run &optional REPETITIONS &rest FORMS)

Time execution of FORMS.
If REPETITIONS is supplied as a number, run forms that many times,
accounting for the overhead of the resulting loop. Otherwise run
FORMS once.
Return a list of the total elapsed time for execution, the number of
garbage collections that ran, and the time taken by garbage collection.
See also `benchmark-run-compiled'.