@WartedSummer2 , thanks for this! I used Glasswire and found indeed that dashost.exe was connecting every minute to the internet. After disabling this service, the stutter was gone. Super!
As dashost (or DeviceAssociationService) is a default Windows service for pairing wired and wireless devices, this sounds to me like a problem at Microsoft. But why do only a few people have this problem?
Anyway, i am glad i found it and was able to solve it. Thank you all!!!