I've been asked to add a function to a huge script that currently takes an age to run.

Note that I haven't been asked to look at performance (and a lot of the blame is on the large amount of data that it has to trawl through), but the Christmas period is usually a bit quiet and I think that a bit of fiddling might improve it, and am looking for confirmation (or warnings to the contrary!).

Firstly, the script initialises about 100 variables once in a while using the following style of declaration: 

$totalamount = 0;
$companyname = "";

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When I look at it, it looks wrong - I want to change them to: 
$totalamount = undef;
$companyname = undef;

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or: 
$totalamount = $companyname = undef;

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Is this likely to improve performance, or does "pre-loading/maintaining" the variable type (integer/string) have some kind of use that I've been ignorant of for the past n years ?

Secondly, the script tests whether string variables are populated by using the length function, which seems a pointless way of slowing the script - e.g. 

if ((length($companyname)>0) && ($anotherstring eq 'DOIT')) { ... }

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This is what I would have done: 
if (($companyname) && ($anotherstring eq 'DOIT')) { ... }

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Any comments appreciated.
Ed

In reply to How does variable definition affect Perl performance ? by EdsterTech

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