It's faster, but not because the pattern itself is faster. You're getting the benefit because your regexp isn't changing, and you're doing the same pattern tens of thousands of times. The loop I suggested doesn't have that benefit.

But it can. 

use strict;
use warnings;
use 5.010;
use Benchmark qw[ cmpthese ];
use List::Util qw[ shuffle ];

our @terms = qw[
    the quick brown fox jumps over the lazy dog
];

our $re = join'', map "(?=^.*$_)", @terms;
$re = qr/$re/;

our @lines = map join( ' ', shuffle @terms), 1 .. 100;
push @lines, ( 'every good boy deserves food' ) x 100;
my $line = join '&&', map {"/$_/"} @terms;

our( $a, $b, $c ) = (0) x 3;
cmpthese -1, {
    a=>q[ /$re/ and ++$a for @lines; ],
    b=>q[ for my $str ( @lines ) { !grep( $str !~ /$_/, @terms) and ++
+$b; } ],
    c=>qq [$line && ++\$c for \@lines;],
};

say "$a:$b:$c";
__END__
    Rate     b     a     c
b 39.8/s    --  -95%  -97%
a  807/s 1927%    --  -36%
c 1254/s 3051%   55%    --
109400:4800:243000

[download]

In reply to Re^8: Regex match at the beginning or end of string by JavaFan
in thread Regex match at the beginning or end of string by cyber-guard

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