I really began consiouly thinking about my own nerdy process after reading The Hustler's Manifesto - TLDR; 1) don't test all your code, 2) stop being such a nerd, 3) take ownership of all your features.
I realized that I easily fell into the traps of 2 & 3 of the manifesto in that (2) even though I'm not the smartest nor most experienced nerd, I love figuring out what's best practice, what little things I can do to tweak to make things more efficient, and generally geeking out. And (3) thinking about cool other features to code up, because I love coding, rather than figuring out how valuable the current implented features are by getting measurable metrics.
I talked to fellow nerd Arthur Chang (Fanvibe/BeRecruited) about it, we discussed it, and I concluded that you should never worry about scalability (at least not in the beginning). It's a waste of time.
Well... actually that line is a little sensationalized. What I really mean is it is usually more harmful than helpful to worry about the little nerdy things in the beginning. The reason is because most problems that you will try to tackle and find a solution for, will only present themselves as real problems if you suddenly get a lot of traction and scale/efficiency really begins to make a difference.
And in the case that things break.. well then you are probably in a good position. With those types of problems, you can probably go out and raise money. And with that money you can go out and hire people to work out those problems while you continue to focus on the vision of your product!
So basically, when the nerd within begins to spend that extra second worrying about efficiency remember that your time is better spent working on getting your product built and distributed. Because most likely there will never even be a sign of a problem - in which case if you spent time working on solving that problem you wasted your time - but if there is a problem then you are ready to raise money to find someone to spend the time solving that problem.
There are definitely plenty of exceptions to this, but I feel that generally following this works. You should definitely make sure there are no gaping wholes in what you're building but don't worry too much about it! Though... do what I say and not as I do. As I will probably fall into this trap.