I think he means, that the Editor takes ages to load the changes he did.
Like when you edit something in the Object Editor, it will take some seconds till it's changed.
You can simply speed this up by deselecting this option:
-> Go to "Window" and remove the mark from "Brush-Palette"
-> It's the hierarchy that shows your Units and stuff in the bottom left corner of the WE
-> When you disable this Hierarchy the Object Editor works a lot faster!