Hi al@xray,
Thanks for coming to Apple Support Communities for help today.
Are you able to test Safari on another network? This can help isolate the issue a little further and help us determine if we need to take a deeper look at Safari, or the internet connectivity on your Mac. Check out: Connect to the internet with your Mac - Apple Support
We'd also recommend testing while started up in safe mode. This will clear cache and eliminate the possibility of login items contributing to the behavior. Here's how: How to use safe mode on your Mac.
Let us know how the performance is in safe mode and after restarting normally: Shut down or restart your Mac - Apple Support
Have a fantastic day!