1. Find bottleneck.

2. Remove bottleneck.

3. Repeat.

4. Every once in a while, make a bold move to throw something out that can no longer work that way and replace it with something more scalable. But while this is important, it comes up less often than you might think.

The difference is that you spend a lot more time in that loop than a desktop dev, but if you understand programming it isn't a special black art until the very, very top end.

The other thing to get is that it's always about buying time rather than solving the problem forever. The goal is to have bought enough time that you don't have to be stuck in a local optima or make panicked decisions.