Reported in #313

@mtojek An other thing that just came to my mind is that as part of the migration we should also start thinking about optimising the dashboards. For example the query for event.dataset should become a query for stream.dataset which is a constant keyword and much more efficient. The gent should always add these fields (@michalpristas will know more if this already happens).
I don't think we need to do all these optimisations directly during the migration but could be done later on. But we should start a checklist with these already now so we don't forget.