My team is currently in the process of trying to switch from 2018.2 to 2018.3. One of our sticking points is the need to edit large quantities of prefabs in code. We have about 400 ability prefabs, and a comparable number for actors. We often need to make systematic changes to all these prefabs at once, such as swapping one component for another and copying over the variables from the old one to the new one. This requires changing and saving all the prefabs in sequence with editor scripts. In 2018.2 this process generally took a few minutes, in 2018.3 it takes about an hour. The increase in time taken is specifically in the process of saving the prefabs after making changes. We have tried with auto save on and off and we have tried using the new methods PrefabUtility.LoadPrefabContents, PrefabUtility.SaveAsPrefabAsset and PrefabUtility.UnloadPrefabContents, but nothing so far has cut down the saving time. With how frequently we need to make these sorts of changes this massively slows down our workflow and makes upgrading to 2018.3 on our master branch unworkable for us, so we'd really appreciate it if anyone has ideas on how to speed up the process in 2018.3, or any indication as to whether the situation is going to be improved in a version of Unity 2019.