Admin Panel very slow

I have set up a local installation on a Win7 x64 system. Apache 2.4.20 and PHP 5.6.21, both in x64 version.
The setup works fine for static HTML, also for PHP. I installed the GRAV core + Admin panel and got it running finally. Created the Admin user in the Admin panel.

When I switch between the pages / plugins / themes etc. panels, it is extremely slow. Firebug gives ~15s for a page load. The CPU load on the local machine is ~0%, no error messages in the Apache or PHP log. I activated PHP opcache, which makes no difference.

However, the GRAV demo pages itself load within milliseconds, also a F5 on the Admin login page is that fast.

Any ideas?

Try turning off the Google fonts in the Admin Plugin settings.

Helps?

Makes no difference, except that the text is somewhat clearer to read now ;-)
This local machine has no internet access right now, so could that be some kind of timeout?
No difference whether I am on the local machine direct, or from another PC (with internet access) via network.

[SOLVED]
The local machine running the Apache server needs internet access, as www.getgrav.org is contacted via 443 on every click in the admin panel.
it is now working fast as expected.

Why is getgrav.org contacted on every click? Seems like a lot of unnecessary traffic

That is not the case. Admin pings the GPM once, to check for updates for core and installed plugins/themes, and caches the results for 24hrs (if I'm not mistaken on the # of hours), so you should definitely not have a request on every click.

Confirmed by testing with my network filter

Pretty sure we have an option in the admin options to disable the check for updates.