Fetch and save operations get pretty slow with even just 10,000 entities (if you touch all those entities). It gets a little better if you pre-fetch all the entities rather than one at a time, but the save is still very slow. Breaking that out into a backround thread is feasible, but as the previous commenter mentions, then you risk momentary divergence between the UI and the backend.
This is fetching every entity by its indexed key. My understanding of saving in a background queue is that during that 1-2 seconds, the ui will still be using the pre-modification data set, so very briefly the ui may appear incorrect, no? Not a huge deal, but if the ui will be wrong, then for our app that would still force us to pause the ui until the save finishes.
