Nothing can replace many, many years of experience. Some skill in general optimization-thinking is key. The ability to visualize how the entire system works is

Nothing can replace many, many years of experience. Some skill in general optimization-thinking is key. The ability to visualize how the entire system works is key. Aptitude for API and general architectural design is key. And even when you get it all right, _something will fail._ At which point profiling and having the right metrics in place so you can see what's failing is key.