Tips to make your game more smooth? (less lag?)

Thought of a couple more:
Disconnect from the Online Features, etc, ie play in Offline Mode.
Clean out your Library/Tray Folder and save it somewhere else if you want a back up, either on your computer, but not in SC4, or on an external storage device.
Clean out your Screenshots Folder. But I moved the entire thing once, and must have messed something up, because my camera didn't work and all my photos were black. I put them all back in and sorted them one by one or a few at a time, and it was fine.