use Benchmark qw(timethese cmpthese);

$url = 'http://www.larryandnatalie.com/isapi.dll/c/content/f/viewproperty/siteid/wb5KAM/contentclass/PICT/contentid/ZZZZZZVR/propertyname/Original/~/yamaha_58_page_11_jpg.jpg';

$r = timethese( -5, {
    'regex' => sub{$url =~ s/^(.{35})(?=.{19}).+(.{15})$/$1...$2/;},
    'substr' => sub{$url = substr($linktext, 0, 35) . "..." . substr($linktext, -15) if length($linktext) > 53;},
});

cmpthese $r;

__END__
Benchmark: running regex, substr for at least 5 CPU seconds...
     regex:  2 wallclock secs ( 5.07 usr + -0.07 sys =  5.00 CPU) @ 633939.80/s (n=3169699)
    substr:  6 wallclock secs ( 4.69 usr +  0.34 sys =  5.03 CPU) @ 3532631.81/s (n=17769138)
            Rate  regex substr
regex   633940/s     --   -82%
substr 3532632/s   457%     --