use strict;
use warnings;
use Benchmark;

my @strings = qw(exception:tex exception:mex asdf tex:exception:mex);

my @one = @strings;
my @two = @strings;
my @three = @strings;

Benchmark::cmpthese( -5, {
    'one' => sub { my @filtered = grep { /exception:(?!tex)/} @one; },
    'two' => sub { my @filtered = grep { /exception/ && !/tex/ } @two; },
    'three' => sub { my @filtered = grep { /exception:/g && !/\Gtex/ } @three; },
});