sub index
{  if ( index('yabba dabba doo','abba' ) >= 0 ) { }
}

sub regex
{   $_ = 'yabba dabba doo';
    if ( /abba/ ) { }
}

cmpthese ( 500_000, 
   {  regex => sub { &regex },
      index => sub { &index },
   },
 );