Last Tested: Sep 6, 2019
Question: Why is my dashboard taking so long to load?
Answer: When we run a dashboard, the query for each tile gets kicked off at the same time. Firstly, we may be hitting the per user query limit or the max connection. Let's say this dashboard has 20 tiles: we would hit the per user query limit which has a default of 15. This means that 15 of those tile's queries would run and the remaining 5 will be queued until a connection thread becomes available. Then as query results are returned. The next query in the queue will run. Similarly with the max connections: if we have max connections set to 50 and 45 user are each running 1 query at the time we run out dashboard - only 5 tile's will run and the queries for the remaining 15 will be queued until connections open up. Secondly, it could be that the query itself is taking a long time to run against the database.
See How to cache a dashboard (Note for Sam and Molly - this is a Community Candidate Guru card) for information on caching a dashboard and the Help Center article Best Practices: Optimizing Query Performance for Optimizing Query Performance in Looker.