And that's not even mentioning the fact that XML::LibXML is 20x faster

BTW. Even that factually correct claim only tells half the story. Generate a simple and fairly modest XML file using this:

#! perl -slw
use strict;

$|++;
our $S //= '999';
our $I //= 10;

open O, '>', 'junk.xml';
print O '<servers>';
for my $s ( '0001' .. $S ) {
    printf "\r%s", $s;
    print O "<station$s>";
    print O '<ip>', join('.', unpack 'C4', pack 'N', int( rand 2**32 )
+ ), '</ip>' for 1 .. $I;
    print O "</station$s>";
};
print O '</servers>';
close O;
[download]

Like this:

C:\test>xmlgen -S=9999
9999
C:\test>dir junk.xml
15/01/2012  12:40         2,424,205 junk.xml
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Now run XML::Simple & XML::LibXML scripts that parse that file and iterate the contents and time them:

C:\test>xmllib junk.xml
Parsing took 0.290895 seconds
Iteration took 171.657306 seconds
Total took 171.959000 seconds
Check mem:63.6MB

C:\test>xmlsimple junk.xml
Parsing took 38.202000 seconds
Iteration took 0.059186 seconds
Total took 38.262577 seconds
Check mem:142MB
[download]

All the time you gained during parsing, you throw away four-fold when accessing the data through the nightmare interface of OO baloney.

And if you double the file size:

C:\test>xmlgen -S=19999
19999
C:\test>dir junk.xml
15/01/2012  12:58         4,868,440 junk.xml
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And now LibXML takes 8 times as long:

C:\test>xmllib junk.xml
Parsing took 0.560000 seconds
Iteration took 676.238758 seconds
Total took 676.802000 seconds
Check mem:107MB

C:\test>xmlsimple junk.xml
Parsing took 75.078000 seconds
Iteration took 0.124583 seconds
Total took 75.209615 seconds
Check mem:254MB
[download]

Increase the file size 10-fold and LIbXML will take 100 time longer.

Now look carefully at the split times. XML::Simple's parsing time is slow, but linear with the file size. It's traversal time is extremely fast and also linear.

Conversely, LibXML's parsing time is very fast and linear; but it's traversal time is horribly slow and quadratic with the file size.

It is easy to see which one wins in the speed stakes.