use Math::Random::MT qw[ rand ];; $filters[ $_ ] = pack 'Q*', map int( 2**64 * rand() ), 0 .. 1562 for 0 .. 99;; say time(); $mask = chr(0xff) x 12504; $mask &= $filters[ $_ ] for 0 .. 99; say time();; 1357485694.21419 1357485694.21907