So in theory, sync time does not depend on how many versions of the app you have.
This is because you are usually syncing the latest version and we save that away separately for rapid retrieval. Now if you are syncing let’s say a stable version, then again, we should be caching that away separately for rapid retrieval. But we have some flaws in this caching logic especially as we have reworked our infrastructure, deployed in a new cloud configurations, etc. But that is in the process of being fixed. So any time you see on app retrieval should soon be minimized.
Independent of all of this, there is still a latency in retrieving large app definitions if you are using the app from anywhere outside North America — because the app definitions are currently stored in North America. This is also being changes to distribute this more globally, via replicas/caches in the short-term, but also via partitioning to better conform to data soveriegnty requirements in the medium-term.