# time /usr/bin/perl > /tmp/foo
use warnings;
use strict;
use File::ReadBackwards;
my $bw = File::ReadBackwards->new( '/var/lib/mysql/ibdata1' ) or
  die "$!" ;
while( defined( my $log_line = $bw->readline ) ) {
  $log_line =~ s/1/2/g;
  print $log_line;
}
__END__

real    0m27.431s
user    0m12.906s
sys     0m10.701s
[root@afflinux aff]# time /usr/bin/perl > /tmp/bar
use warnings;
use strict;
my $FH = undef;
open($FH,  '/var/lib/mysql/ibdata1' ) or
  die "$!" ;
while( my $log_line = <$FH> ) {
  $log_line =~ s/1/2/g;
  print $log_line;
}
__END__

real    0m5.249s
user    0m1.535s
sys     0m0.293s