Ok, so I’ve been running some tests on your server.
When you go to the “Plugins” area of the Dashboard, each plugin sends a message back home to see if there’s a new update – each check should take around .5 of a second. This goes for every single plugin you have – not just GP add-ons.
Naturally, if you’re going to want all 11 add-ons installed and activated, it’s best to upgrade to GP Premium, as it will only send 1 message home as opposed to 11.
However, even with all 11 add-ons installed and activated, it should still only take anywhere from 6-10 seconds to load.
Your installation is taking 40 seconds to load the Plugins page.
I believe this is happening because you’re using multi-site, and it’s not only sending a message home for each add-on, but it’s doing it for each site you have within the installation.
I’ve started a thread with the developer of the licensing/updating plugin, so I’ll hopefully be getting his advice on this ASAP.
I’ll update you here with what he tells me 🙂