As Laurent_R said, store the words into a hash for a fast look-up

#!/usr/bin/perl
use strict;
my $t0 = time;

# build dictionary
my $wordfile = 'words1.txt';
my %dict = (); 
my $count = 0;
open my $in,'<',$wordfile 
  or die "Could not open $wordfile : $!";
while (<$in>){
  chomp;
  my ($motlexique,@cols) = split /\t/,$_;
  $dict{$motlexique} = \@cols;
  ++$count;
}
close $in;
print "$count lines read from $wordfile\n";

# scan text file
$count = 0;
my $textfile = 'text1.txt';
open my $in,'<',$textfile 
  or die "Could not open $textfile : $!";
while (<$in>){
  chomp;
  my ($searchword,@cols) = split /\t/,$_;
  if (exists $dict{$searchword}){
     my $genre  = $dict{$searchword}[3];
     my $nombre = $dict{$searchword}[4];
     #Do some things here
     print "Matched '$searchword' to $genre $nombre\n"
  }
  ++$count;
}
close $in;
my $dur = time - $t0;
print "$count lines read from $textfile in $dur seconds\n";
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