Performance, Scaling, and Reliability

Part of the Vibe Coding course

At some point the code has to be fast enough, handle enough load, and stay up when things go wrong. AI is a strong thinking partner here, but it is also where its confident-wrong tendency does the most damage, because performance intuitions sound authoritative and are easy to get wrong.

The oldest rule in performance work: do not guess where the slow part is, measure it. A profiler or a simple timer tells you where the time actually goes, and it is almost never where you expected. Optimizing the part that feels slow, instead of the part that is slow, is wasted effort. ...