I think I figured out the reason of the issue on hand.
The visable and slow reloading of page elements only occurs when there is a dataview, datasource type = microflow on a page container, like a groupbox or f.i. a snippet on just a layout container.
The reloading is as good as in the older versions of the modeler when the dataview is a type = Entity (path).
This issue is introduced in the BM 5.10.0 version, with older versions (5.9.1 and earlier) the reloading was OK.
After doing quite a lot of rework I succeeded in 'solving' the issue by minimizing the use of dataview/datasources type = microflow where ever possible.
Not in all cases that was possible though, so I think I file a ticket for this.
I have not experienced issues like this - in fac my page loading has speeded up. For my applications, this is an improvement in the user experience