Not only due to electricity, but also the high rate of replacing perfectly working computing equipment for higher-performing, only to spend any additional capacity running increasingly crappy and demanding software.
A valid point, but that just kicks the same question down the road: why was no engineer assigned to investigate loading times? That might be indicative of a culture that is biased towards projects with an outcome decided a priori. A lot of managers don't want to assign tasks where the definition of "done" is ambiguous.
Almost every employer also has a bunch of things they'd like you to do outside of your stories - mentoring junior developers, recruiting, planning, team building, professional development.
Some employers have SOC2 compliance policies that all changes should be traceable to a documented requirement, so fixes after the change is complete can be a bit more bureaucratic. If the project is behind schedule, the bosses might want you to work on something else instead.
Many developers are given pretty high-spec machines, so they can compile quickly and run weighty IDEs and so on - meaning an issue that's painful for users with 2GB of RAM and 2 CPU cores might be barely noticeable to users with 32GB of RAM and 8 cores.
And of course, some workplace cultures would say if you've 'got your work done' you can do discretionary performance work or you can leave early - and who'd choose performance work over spending time with their loved ones?
At that point, every developer on the team becomes an interchangeable useless warm body and the promotion goes to the "rock star" from outside who comes in and rewrites it or surgically fixes the top performance issues.
Sadly, the people I report to don't care enough about it. All they want is to push through the visible changes as fast as possible. And every single time these performance bugs come to bite us.
Our solution? Scale the system resources.
I'm not particularly satisfied with the work. But as an engineer I don't get to call the shots.