By looking at Extended Events i found some interesting Events in a category called Query…
The first day at PASS 2019 and I was on a seminar about Query store and monitoring performance on queries via that. It is really interesting what you can do and how you can monitor plans etc. But that is another post.
What was also talked about was when SQL server is starting. Then the information in the query store needs to be read into memory before SQL server can start executing queries. That is usually not a problem with a small Query store but it could be a problem with a large Query Store.
The fix for this is to add a trace flag. Namely TF 7752. This lets the Query Store to be loaded asynchronously. Then SQL server can start executing its queries much faster and does not have to wait before Query store is completely loaded.