##do something with $p - 1 while $p = 1 + index( $haystack, $needle, $p );

##</code><code>##

$s = 'the quick brown fox jumps over the lazy dog'; 

cmpthese -1,{
    a => q[ if( $s =~ m[(lazy)]){ $found=$1 }         ],
    b => q[ $found = 'lazy' if 1+index( $s, 'lazy' ); ],
    c => q[ $found = 'lazy' if $s =~ 'lazy';          ],
};;
       Rate    a    b    c
a  577066/s   -- -77% -79%
b 2492720/s 332%   -- -11%
c 2791311/s 384%  12%   --
[0]{} Perl>

##</code><code>##

$s = 'the quick brown fox jumps over the lazy dog'; 
$x = 'lazy'; 
cmpthese -1,{
    a => q[ if( $s =~ m[($x)]){ $found = $1 }   ],
    b => q[ $found = $x if 1 + index( $s, $x ); ],
    c => q[ $found = $x if $s =~ $x ],
};;
       Rate    a    c    b
a  449697/s   -- -79% -82%
c 2167332/s 382%   -- -12%
b 2462877/s 448%  14%   --

$s = 'the quick brown fox jumps over the lazy dog'; 
$x = 'lazy'; 
cmpthese -1,{
    a => q[ if( $s =~ m[($x)]){ $found = $1 }   ],
    b => q[ $found = $x if 1 + index( $s, $x ); ],
    c => q[ $found = $x if $s =~ $x ],
};;
       Rate    a    c    b
a  459542/s   -- -79% -80%
c 2184810/s 375%   --  -6%
b 2318112/s 404%   6%   --