Making Programs Faster

`time()`

Wallclock time is measured by Perl's built-in time() function:

        use LWP::Simple 'get';
        my $url= shift;
        my $start = time();
        my $doc = get($url);
        my $elapsed = time() - $start;
        print "$elapsed second(s) elapsed.\n";

        2 second(s) elapsed.

It returns the amount of time that has elapsed since the beginning of 1970
By default, the resolution of time is only one second
Related: $^T variable contains the time at which the program started

     print "Program has been running for ", 
                time() - $^T, " second(s).\n";