Hello Jaap,
I am also referring to the V2-Set.
It seems your server (Apache) does neither have mod_expires, nor mod_headers extensions activated. In YSlow V2, this is the reflected by the point “Add Expires headers”. The htaccess-commands should turn those on, using any of those mentioned modules. Perhaps you want to check with your hoster?
This will help considerably.
But… In your special case I’d think you’ll probably still miss the 90ies in YSlow V2 as your site is really cluttered with javascripts (Google Adwords + Analytics), pictures from everywhere, and fully stuffed with Plugins (flexibility seems to create many additional requests on its own).
Still: the most important point is that your page is working as expected, perhaps a little faster than before.
Regards from non-swiss-speaking Germany ?? over to Belgium or Holland?
Schepp