I definitely hit my coding peak somewhere in my late 30s. I don’t know how much slower I actually am, vs how much less I care. For one, I care to not write code that I’m not going to use. I spend way more time planning, talking about, and mulling over the thing I want to build, and I generally get it right the first time. Maybe part of the lesson of experience is not being in such a rush. Second, I’ve written so much code that I just don’t care as much about that activity as I used to. When I’m properly motivated to do something I still feel quick and energetic. I’m learning ASL with my girlfriend and she’s frustrated that I move faster than her, at some 13 years her senior. Maybe it will catch up to me eventually.

These statements really ring home when i'm thinking about my 20s and coding.

Back then, i'd dive right in, start coding, prove what works, figure it out as I go, then have to adapt the existing code to the figured out design. I was much more attached to that code and didn't want to lose it. Today, if I write code, I plan it out, have a good idea of how the pieces will work and then go implement it. And honestly, if the code gets thrown away, it's not the end of the world.

Code is really a small portion of what engineers do...

Chess players peak in their late 30s too.