Your dashboards are now more responsive and load faster with improved caching. Dashboard query results are now cached, increasing performance with fewer calls to the server.
Where: This change applies to CRM Analytics in Lightning Experience and Salesforce Classic. CRM Analytics is available in Developer Edition and for an extra cost in Enterprise, Performance, and Unlimited editions.
How: Improved dashboard caching in the default behavior. If necessary, you can turn it off. From Setup, in the Quick Find box, enter Analytics, and select Settings. Select Disable dashboard query caching.
Get Improved Dashboard Performance with Better Caching (salesforce.com)