Using twerq's original script, I got similar results on an ActiveState Perl/Win32 machine: my was more than twice as fast as local.

However, I modified twerq's script so that each variable is only declared once. Here is the modified script, which measures time to access or change variables rather than to declare them: 

# replace local with "my"
local $start_time = time;
local $global_variable = "hello!";

for (local $i = 0; $i < 5000000; $i++) {
              $global_variable = "redefined. . ";
}
print time - $start_time." seconds\n";
print "$global_variable\n";

[download]
The program now takes 24 seconds when local is used and 18 when my is used. So it appears that local can introduce significant overhead into a program even when the program only declares variables a few times but accesses them over and over.

In reply to Re: Re: is 'my' that much faster than 'local'? by sierrathedog04
in thread is 'my' that much faster than 'local'? by gregw

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