Quickly spawning many physically simulated replicated actors

Development Programming & Scripting C++
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In our project, there can be many (dozens up to hundreds) physically simulated actors that players can interact with in a small area. They are spawned dynamically over the course of a session. But when a new player joins or a saved game state is loaded on the server, all of these objects are spawned at once.

For the clients, getting all the objects replicated takes a while (seconds even for dozens of objects with server and client on the same pc). Is there a configuration option or some other way to speed this up?

Since getting all the objects replicated takes so long, the physics simulation can go badly out of sync during this time (e.g. one actor lying on top of another is replicated before the lower actor, so the upper actor will fall down). Therefore, I want to stop the physics simulation until all the actors are replicated. I figured out a way to pause the physics. SetSimulatePhysics(false) for all affected objects produces artifacts (objects fall through each other when I reactivate the simulation), but constraining movement on all axes works. However, how do I know when to continue the simulation? How do I figure out when all objects on the server are successfully replicated on all clients?

There’s a recent similar question here: Is there a way to make a progress bar for replicated actors? - C++ Gameplay Programming - Unreal Engine Forums
So far, it hasn’t received any answers unfortunately.

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If someone else stumbles upon this thread: I have found a solution to determine whether all objects have been replicated. You can get an instance of UPackageMap from a UNetConnection. E.g. in a PlayerController call GetNetConnection()->PackageMap. On that object, you can call GetNetGUIDFromObject(obj) for each object that you want to check. It will return a FNetworkGUID where IsValid() is true for objects that have been replicated. I check for every relevant object whether I get a valid GUID. When that is true for all objects on all connections, I know that the replication is done.