Postpone syncing of particular file which has already started syncing

I am currently using Syncthing over a slow connection, and I have 2 files in the queue - one big and one small. The small was created later then the big one and the big one has started syncing already. I see no easy way to "pause" the sync of the big file to allow small file to get synced first (I want it first, because the big one will take 2 days to sync). I tried changing the pull order but it does not affect already started transfers - the app restarts and continues syncing the big file.

Wouldn't this be a useful new feature?

Start by reproducing the queue with one large and one small file over a slow connection, then inspect the existing pull-order behavior and what happens when the app restarts during an active transfer. Determine how an already-started transfer could be postponed without losing progress, and define completion as allowing the smaller file to sync first while preserving correct recovery of the larger file.