time_expression() - return the amount of real time that an expression took
int time_expression( mixed expr );
Evaluate <expr>. The amount of real time that passed during the evalu‐ ation of <expr>, in microseconds, is returned. The precision of the value is not necessarily 1 microsecond; in fact, it probably is much less precise.
rusage(3), function_profile(3), time(3)