When there are too many (100k+) rows of data visible on a dashboard containing an extension, this might cause issues. The dashboard can get stuck loading, or the extension itself can become unresponsive after the dashboard has finished loading.
The reason behind this is the extension API attempting to scan the data visible on the dashboard when a dashboard with an extension is loaded. Too much data can cause the API to become stuck, and eventually time-out.Solution: reduce the amount of data visible on the dashboard using filters or views.