You didn't mention whether you were on Win32 or Linux. The time() function will let you calculate elapsed time in 1-second increments.

On Win32, if you want something with more resolution than that, you can use the Win32::GetTickCount() function, which is built-in and doesn't require you to use any modules.

my $start = Win32::GetTickCount();
long_function();
my $end = Win32::GetTickCount();

printf("function took %01.3f seconds\n", ($end - $start) /1000);
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