Expanding Dashboard Group Delay

I noticed that when I expand a collapsed dashboard group, the page freezes for a few seconds (a noticeable delay) until it shows the metrics and returns to normal. We are querying data from a local telegraf DB. The number of dashboards that were collapsed/contained within the group were 2-4. The queries we pretty simple.

If I leave the dashboard with all groups opened this of course will not happen.

Any explanation?