BrowserUk:

Ummm ... you want to reverse those or clauses, otherwise the second clause in your or won't run.

#!/usr/bin/perl
use Benchmark qw(cmpthese);
$substr = join('','a'..'j');
$str = $substr x 90 . 'hTmL'. $substr x 2000;
print "length of search string: ",length $str, "\n";
cmpthese(-3, {
        'Fregex ' => sub {
                $str =~ /^\A.{0,996}?html/si
                or $str =~ /^\A.{0,996}?sgml/si;
        },
        'Fsubstr' => sub {
                substr( $str, 0, 1000) =~ /sgml/i
                or substr( $str, 0, 1000) =~ /html/i;
        },
        'Findex ' => sub {
                1+index( lc substr( $str, 0, 1000 ), 'sgml' )
                or 1+index( lc substr( $str, 0, 1000 ), 'html' )
        },
        'Rregex ' => sub {
                $str =~ /^\A.{0,996}?sgml/si
                or $str =~ /^\A.{0,996}?html/si;
        },
        'Rsubstr' => sub {
                substr( $str, 0, 1000) =~ /sgml/i
                or substr( $str, 0, 1000) =~ /html/i;
        },
        'Rindex' => sub {
                1+index( lc substr( $str, 0, 1000 ), 'sgml' )
                or 1+index( lc substr( $str, 0, 1000 ), 'html' )
        },
});
print substr $str, 900, 10;
__END__

root@swill ~/PerlMonks$ ./string_search2.pl
length of search string: 20904
            Rate Rregex  Fregex  Rsubstr Fsubstr Findex   Rindex
Rregex   48562/s      --    -35%    -54%    -54%    -55%    -55%
Fregex   75225/s     55%      --    -28%    -29%    -30%    -30%
Rsubstr 104700/s    116%     39%      --     -1%     -2%     -3%
Fsubstr 105896/s    118%     41%      1%      --     -1%     -1%
Findex  107056/s    120%     42%      2%      1%      --     -0%
Rindex  107434/s    121%     43%      3%      1%      0%      --
hTmLabcdef
root@swill ~/PerlMonks$
[download]

Update: Had I used my brain, I'd've changed the $str definition to use 'sGmL' rather than edit the function definitions....

...roboticus

There are lies, damned lies, and benchmarks.