Occasionally massive editor lag (probably webview)

Unity 2018.4.4f1

Once every 1-3 minutes I get a 5 second lag in the editor. Profiling unfortunately is no help because apparently there are no tags in the affected function (see screenshot). I tried with an empty project, same issue. I didn't have the problem initially with 2018.4.4 and the lag is always 5 seconds which feels like a network timeout. This is usually followed by a 10 second webview tick. So I assume its connected to some external service such as the asset store webview, unity hub or the package manager. However, this issue also occurs when the asset store window / hub is closed.

 

We have a similar issue in 2019.4, anyone know what is the problem and how to fix it?