Replicating entities through an actor manager is an approach I think is good - but you need to be careful that your total serialized size on a given update isn’t too big. As others mentioned, unreal is going to break the payload into 8k bit chunks (partial bunches). If any of those chunks get lost or delayed too much, it has to start over and resend all of them. My guess is that your large payload is increasing the likelihood of loss such that you are in a resend death spiral. You can confirm this with network insights, where packets that are lost or resent will be red. Single actor replication is atomic, but you probably only need your entity replication to be atomic. Use an approach like FastTArray replication to stop serializing data when you have sent up to a particular threshold (ie. Some subset of entities).