Probably the worst thing about actually getting in to work early when there's no reason to is the fact that it's that many more hours before lunch. Normally, you have a set of rituals that will take you up to a reasonably later moment in the morning. By that point, it's not that bad a stretch until lunch, with or without stimulants.
Right now, I can feel the boredom seeping in even though I have plenty of work.
Regardless of how nice leaving at 3:30 or so is, I think I'm going to stick with coming in at 9. Life is so much simpler that way.
The solution is to eat lunch at 10 AM.