This logic sounds like the important part of your application, but I don't get it yet. Why does the user care about the position of their post relative to some

This logic sounds like the important part of your application, but I don't get it yet. Why does the user care about the position of their post relative to some other post? Could it be approximate instead? Also, does it have to be accurate up to the second, or would a slower update cycle work? I feel like maybe you could make some very small changes to the algorithm, and make it much more tractable on the backend.