use v5.10;

use Time::HiRes qw(time);
my $inputA = "X".(" \t" x 10000)."A    " . ( " " x 10000);

my $start = time;
(my $t1 = $inputA) =~ s/[\s\u200c]*$/ A/;
say time - $start;

use re::engine::RE2;

$start = time;
(my $t2 = $inputA) =~ s/[\s\u200c]*$/ A/;
say time - $start;

say "gleich: " . ( $t1 eq $t2 );