OK, i probably found the reason why there is no internet for 30 seconds on "de-hibernation" of Windows 10 with Opera.
I deactivated, stopped the service superfetch with services.msc and set start type to manual, nit automatic.
After restart from hibernation now i got Internet at once! 🙂
This could be the solution.
If Windows gets slower through deactivating superfetch is still not clear.
I think it is useful at all, but not for Opera, all Chrome Browser engines running with Blink, a fork of the WebKit engine.
This i have to report to Microsoft.
So i will test it a while.