Update - Disconnects and Latency Issues

Stackable items have item ID's? Whatever for?

Because all items have IDs. It's a database, you can't just opt out of certain things generating identities. You have to have some unique way of identifying and referring to the object in memory after all, otherwise how would you tell one from the other? Just because they stack you don't suddenly not need to tell them apart.

Stackables have the most overhead, since they have to destroy one version and increment the counter of the survivor when merged, then spawn a new item and a new id when separated.