Waiting on your application is something every user dislikes. Especially with reporting functionalities or integrations. You as a developer are challenged with the performance versus the business needs. What if you can change the user experience?
I faced those challenged also, espacially when the data needed to be real-time from an external source. Mendix just shows you a loader functions for the complete page, while only a part is of the page is slow. Therefor we developed a widget to change the page loading in Mendix to be more effective.
Read the blogpost https://www.appronto.nl/over-appronto/blog/speed-up-your-mendix-page-load-time or download the widget from the appstore https://appstore.home.mendix.com/link/app/50833/Appronto/Dataview-Loader