material cost increases after save

when i close the mat and reopen the cost decreases. and when i move a node to save it again the cost increases. what is the logic behind this situation ( UE 4.12.5 ).

This has been the case since… well… forever.
I think the value’s you see after saving also take some other content into account (tangent vs world space normals, etc)

The exact reason why this happens… I dont know, but I do know this has been around since the beginning of time… well… a little less than that.

So what is the correct cost for packaged project? before or after?