Windows 11 slow internet connection Dell/Killer Network

After updating to Windows 11 I experienced a very laggy browser on all my favourite websites. But every speed test I did was ok. After some digging, I found the solution in the Microsoft Techcommunity. In a lot of Dell PCs they use Killer Network Adapters. My XPS 8940 has a builtin Killer E2600. After disabling the Killer Network Service all was ok again.