Unfortunately, you didn't say why the file is so large, i.e. what part of the structure is repeated many times. If it's the termEntry , turning your code to use XML::LibXML::Reader is rather easy: 
#! /usr/bin/perl
use warnings;
use strict;

use XML::LibXML::Reader;

print "Importing...\n";

my $file = 'my.xml';
my $reader = 'XML::LibXML::Reader'->new(location => $file) or die;

my $entry_pattern = 'XML::LibXML::Pattern'->new('/martif/text/body/ter
+mEntry');

while ($reader->nextPatternMatch($entry_pattern)) {
    my $termEntry = $reader->copyCurrentNode(1);
    for my $lang_set ($termEntry->findnodes('langSet')) {
        my $language = $lang_set->getAttribute('xml:lang');
        for my $term_grp ($lang_set->findnodes('./tig')){
            my $term = $term_grp->findvalue('./term');
                print "$language: $term\n";
        }
    }
}

print "Done!\n";

[download]

Tested with the following input: 

<martif>
  <text>
    <body>
      <termEntry>
        <langSet xml:lang="en">
          <tig><term>English</term></tig>
          <tig><term>Saesneg</term></tig>
        </langSet>
        <langSet xml:lang="cs">
          <tig><term>Czech</term></tig>
          <tig><term>Tsieceg</term></tig>
        </langSet>
        <langSet xml:lang="de">
          <tig><term>German</term></tig>
          <tig><term>Almaeneg</term></tig>
        </langSet>
      </termEntry>
    </body>
  </text>
</martif>

[download]

Reader is a pull parser that doesn't need to load the whole file into memory, but while walking it, you can ask it to inflate the current node into the whole DOM object (which is what copyCurrentNode(1) does.)

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: XML::LibXML out of memory by choroba
in thread XML::LibXML out of memory by Anonymous Monk

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