Instrument your business. It's like instrumenting your code, but profitable.
If you're a developer or a sysadmin, periodic optimization is a fact of life. As more people use your code, you'll see performance issues. Unoptimized use cases bubble up. Systems get strained by continued or heavy use.
On the technical front, there are a lots of instrumentation tools available. We've used ruby-prof, Request Log Analyzer, Scout (of course), MySQL Tuner, httperf, and Rack::Debug. Not to mention low-level tools like top, vmstat, iostat, etc.
The point is this: anything that gets used a lot can be optimized. To optimize you need visibility. To get visibility, you need tools.