Okei, i have figured out that our IE webcache is generating a long logontime. In UEM Personalization/INternet Explorer i have these settings:
[IncludeFolderTrees]
<Cookies>
<Favorites>
<LocalAppData>\Microsoft\Windows\WebCache
And the webcache.dat its about 26mb, and generate 15-20 seconds longer logontime, but as far as i have figured out, i need this DAT file because users credentials and history are stored here. If i remove this setting, users have to input username and password for every sites they want IE to remember...
Thats my bottleneck as we speak, but i'll have a closer look at you suggestions as well.