There are currently intermittent page load issues on the German Wikipedia. These can be caused by HTML documents loading slowly, especially on special pages, or resources loaded through the resource loader. I am seeing page load times of upwards of 150 seconds.
The issue affects different users with different browsers and internet service providers. The problem has appeared before, for example on 6th/7th June 2019. At the time, it was explained to be related to ongoing software deployments on WP:Fragen zur Wikipedia.
Update: Evidence so far suggests that users in several European countries are affected, including Switzerland, Germany, Finland and France. This would probably point to some problem in the Amsterdam cluster.