man 3 time

time(n)                      Tcl Built-In Commands                     time(n)

______________________________________________________________________________

NAME
       time - Time the execution of a script

SYNOPSIS
       time script ?count?
_________________________________________________________________

DESCRIPTION
       This  command  will  call  the  Tcl interpreter count times to evaluate
       script (or once if count isn't  specified).   It  will  then  return  a
       string of the form
              503 microseconds per iteration
       which  indicates  the average amount of time required per iteration, in
       microseconds.  Time is measured in elapsed time, not CPU time.

KEYWORDS
       script, time

Tcl                                                                    time(n)