In cases like this I have a server call that fetches a variable number of items.
The form_show event fetches a small number of items and shows them immediately, then either the tick event of a timer or the mouse wheel event will read another number of rows. I just went back and searched a post where I describe something similar, and look, you contributed to it too, thank you!! 
This would ensure one roundtrip only for the first items to be displayed and a second trip for the remaining items. There will never be additional trips done at the whim of the logic behind the row objects.
But you already knew this, my old post has your very own contribution, so if you think it’s unsuitable for your current use case, well, I’m sorry I don’t have an answer.