I think I was quicker and smarter when I was younger. Now I have experience and a broad skill set with which my younger self would not be able to compete. And in ten years from now I plan to be saying that again about my current self. The stuff I produce now is rock solid and well architected. I don't need to work 12-15 hour days because I know how to get things done right, I know the appropriate solutions for a wide variety of problems. I know what works and what doesn't.
1. Seeing the big picture. It used to be about the technology; now, it's about people. Technology is the means to an end, not an end in itself (usually; sometimes playing is just fun).
2. Predicting pain points. School of hard knocks and all that. I've also seen a lot of technological change from my first BASIC programs on a TRS-80 and Atari 600, which informs that.
3. Knowing when to be passionate. Some things really matter; others, not so much. Those things that matter need the time and energy they deserve; the things that don't matter, well, don't. I'm much better at letting unimportant things go under the bridge, freeing time, energy and mental capacity for more important things.
This does mean it doesn't come without a cost. Here are the tradeoffs (for me, not speaking generally):
1. Much less time available. Life competes, kids have plays and soccer games, yard work has to happen, etc.
2. The desire to beat my head against a problem for 96 hours straight has waned significantly. I'm much more likely to go off and do something else and come back to it later.
3. Learning is different. It's not slower, but the process is different. For things that have a positive pattern match from the past, learning is very fast; but if there is no pattern match, it takes more repetitions to make it stick long term.
Over all, I think I'm a much better software developer today than I was 15 years ago. My code is better, stronger, faster, and I'm not running in circles as often.
In my case, I thought I was smarter when I was younger. In hindsight it turns out I was just better at academic problem solving due to proximity of practice and my solutions/plans were rather shallow.
