A note on browsers and Dashboard performance
Dashboards are grouping of individual reports that are queries to the database. Web Browsers have certain limitations on the number of calls or concurrent threads they can perform against a web server host domain. If your dashboards contain several reports, the web browser you select has an impact on how many queries can be sent concurrently via the web server to the database which impacts how quickly a dashboard can render those reports. This issue is referred to as "Windowing".
The takeaway is that when designing your dashboards, consider creating multiple dashboards with fewer reports on each dashboard rather than creating one large dashboard with many reports. The loading time for each dashboard will be enhanced and so will your user's experience when viewing those dashboards.