remember the adage -- you can perhaps write faster programs in C, but you can most always program faster in Perl.

Perl is easier than C. Make it even easier for yourself. Unless you have a million line Amazon.com kinda code that is being hit by 28,000 users every minute, you shouldn't give a rat's batuti that you are able to shave off another 15 milliseconds from your code by converting $do_this_thing to $d.

You might, however, want to spend an extra 35000 ms thinking about the names... for example, I try to make the variable names about the same length (without getting into unreasonable contortions) just so they line up nice and neat. Neatness in code always improves readability which directly contributes to the adage mentioned above.