I came across FFI::TinyCC and FFI::Platypus recently. The Alien::TinyCC module is what compiles the C code and does so very quickly in memory.

This demonstration completes in 1.832 seconds, ahead of tr.

use strict;
use warnings;

use Time::HiRes qw( time );

# -------------------------------------------------------------------

use FFI::TinyCC;
use FFI::Platypus::Declare qw( string int );

my $tcc = FFI::TinyCC->new;

$tcc->compile_string (q{

  int filter_str ( char* str )
  {
    char* p = str;
    int   i = 0;

    /* strip chars in-place */
    while ( *str ) {
      if ( *str == '[' || *str == ']' || *str == '\'' ) {
        str++;
        continue;
      }
      *p++ = *str++;
      i++;
    }

    return i;
  }
});

my $address = $tcc->get_symbol('filter_str');

attach [ $address => 'filter_str' ] => [ string ] => int;

# -------------------------------------------------------------------

my $doc = "'C-3PO' or 'See-Threepio' is a humanoid robot character fro
+m the [[Star Wars]] universe who appears in the original ''Star Wars'
+' films, the prequel trilogy and the sequel trilogy.\n";

$doc .= $doc for 1 .. 22;       ## expand string to 724 MB

my $doclen = length $doc;
print  "length   : $doclen\n";  ## 759169024

my $start  = time;
my $newlen = filter_str($doc);

## resize string to its new length
substr $doc, $newlen, $doclen - $newlen, '';

printf "duration : %7.03f secs.\n", time - $start;
print  "length   : $newlen\n";  ## 708837376
[download]

Well, curiosity got to me and the reason for trying TinyCC for the first time :)