I think you and I interpret "premature optimization is the root of all evil" quite differently. To me it doesn't mean you should write slow code, but rather tha

I think you and I interpret "premature optimization is the root of all evil" quite differently. To me it doesn't mean you should write slow code, but rather that you shouldn't omptimise a piece of code before: 1. You actually got it working and you know you need it (so you don't waste your time). 2. You profiled the system and you know the code you are optimising is actually making things slow, and it being slow matters. This applies to every metric, not just performance. For example: don't optimise your top of the funnel when your bottleneck is actually conversion. So measure, and then optimise. Don't optimise prematurely.