time_expression

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)