Released in version 1.6 (03 March 2020)
Each dropdown reference selector on a page will trigger a retrieve list action to load all selectable objects. Therefore having too many widgets on a page can have a big impact on performance. It is recommended to replace dropdown selectors with a page popup. This is especially problematic if a reference selector is used inside a list or template grid. When we count the amount of reference selectors we multiply by the number of rows and or columns in a list or template grid.
For more details check the Mendix webinar on app performance https://ww2.mendix.com/expert-webinar-deep-dive-into-xpath.html (min 25).
Non-compliant example:
Compliant example:
Convert from select using Dropdown to Page. Alternatively, remove the reference selector all together.