One of the highly expected changes is optimization of pages. With the upcoming major version (2020 Wave 1) there should be a lot of changes to the behaviour and performance in pages.
In the current version (2019 Wave 2 and older) the page is not opened till all data are loaded. So if the loading process is longer than usual, the user may feel the system is not responding.
With the improvements in 2020 Wave 1 the page opens without waiting for data. Once data are loaded, the page is updated and data shown. If the user close the page and open again, the page load cached data first then, and then, when new data from DB are loaded, the page is updated with new set of data. The cache is stored throughout the session only, so if user’s session end (for example due to inactivity) all stored caches are destroyed.
Collapse / Expand Lines on any page
Another much-needed change in behaviour on pages was the ability for users to collapse subforms, especially in documents. This functionality add users more ways how to optimize pages on which they are working and if they don’t need subforms they have much more spaces for other tabs.
All released or planned features from Microsoft Dynamics 365 Business Central 2020 Wave 1 could be found on Microsoft Docs.