I'm paraphrasing, but the response I got was roughly 'don't worry, we can just run it on a powerful VM' and also the classic 'developer time is more valuable than CPU time'. I have a personal experience where I raised doubts about an unoptimized algorithm (the time complexity was something like O(n^2 log n) where typical case n was supposed to be 10^6). Even when you point out a problem like this, people seem to be unwilling or incapable of understanding it. They just hack things together, gluing libraries on top of frameworks, with very little understanding about what goes on underneath. I would argue part of the problem is that the majority of developers are computer science illiterate. Somehow this gets past code review and QA and into production, where it remains broken and nobody has fixed it. I could sort of understand this sloppiness if it was some random app from a hot startup, but this is a Windows issue affecting, presumably, all Windows users.
Laying out icons on a grid should be an inherently linear operation, but somehow it was written as quadratic and was executed even when the icons were not being displayed.