Interestingly (or possibly not), since my very first computers had ~4K of RAM, I became adept at optimizations of all kinds, which came in handy for my first job - coding 360 mainframe assembly. There, we wouldn't be able to implement our changes if our terminal applications (accessing DB2/IMS) responded in anything greater than 1s. Then, the entire system was replaced with a cloud solution where ~30s of delay was acceptable.

I think the Internet made 'waiting' for a response completely normalized for many applications. Before then, users flew through screens using muscle memory. Now, when I see how much mouse clicking goes on at service counters, I always think back to those ultra-fast response time standards. I still see a few AS/400 or mainframe terminal windows running 'in the wild' and wonder what new employees think about those systems.

It's getting ridiculous. I know SPAs aren't to blame specifically, but it feels like whenever the 2003 page-based web interface is replaced with the modern SPA each action takes forever to load or process. Was just noticing this on FedEx's site today.