But how much does that matter?

If you're scaling to 1000s of users then yes. If you have a GUI for a monthly task that two administrators use, then no.

The less something gets used the longer the payback time on the initial development.

You’re not wrong, but today’s software is so slow/high latency so often, despite incredibly powerful hardware, that as a rule it should absolutely matter.

Maybe it's because they used AWS Lambda and API Gateway for the API?

> If you have a GUI for a monthly task that two administrators use, then no.

Fine, but be honest with yourself and admit that you are contributing a lot to making the lives of those two admins miserable.

It doesn't matter if I'm using your software once a month, or once a day. If it's anything like typical modern software, it will make me hate the task I'm doing, and hate you for making it painful. In fact, shitty performance may be the very reason I'm using it monthly instead of daily - because I reorganized my whole workflow around minimizing the frequency and amount of time I have to spend using your software.

> Fine, but be honest with yourself and admit that you are contributing a lot to making the lives of those two admins miserable

The funning thing is I'm thinking of a specific case and I work closely with those admins. I even have filled in for them when they're sick. Yes I know it's a pain, they know it's a pain, and they let me know it's horrible. The only reason this one is monthly is that it's a stock take. They forgive the crappy performance as it still saves hours of work when compared to the previous manual option of entering things into multiple systems.