if ("\U$listaccountlocked[1]" eq 'TRUE') {

##</code><code>##

sub slashU {
     my $cnt=0;
     for (@words){
             ++$cnt if "\U$_" eq 'ABCB';
     }
     return $cnt;
}

##</code><code>##

In 4096 words, 16 are 'abcb'
        Rate slashU  uccmp  regex
slashU 321/s     --   -18%   -26%
uccmp  390/s    21%     --   -10%
regex  435/s    36%    12%     --
In 4096 words, 0 are 'abcb'
        Rate slashU  uccmp  regex
slashU 328/s     --   -17%   -25%
uccmp  397/s    21%     --   -10%
regex  439/s    34%    11%     --
In 4096 words, 4096 are 'abcb'
        Rate  regex slashU  uccmp
regex  266/s     --    -6%   -18%
slashU 282/s     6%     --   -13%
uccmp  325/s    22%    15%     --