The general problem though is that "and that doesn't matter" isn't backed up by anything but gut feeling.
When FB dove into the numbers, they found they could save 50% in hardware costs. That _does_ matter.
It may be the case that your company has a 20k server rack to support 20M of sales and so it doesn't matter. But unless you've actually looked up the cost you shouldn't be making the claim because it's unbacked; it's just a bad faith arguement.
The cost to rewrite your system to be twice as fast is about the same if you have 20k of hardware costs or 20M, but one saves 10k and the other 10M. Only one offsets the cost of the programmers
The argument is not that performance optimization does not matter at all, but rather than low-level performance optimization, like rewriting compilers, writing your own custom storage system, or rewriting it in unreadable speed-optimized C++ is worth it.
You don't need to do a deep analysis to tell if optimization is needed or not, it is enough to assume best-case improvements and compare it to your FTE + overhead cost.
Do you have many of your servers run CPU-bound C++ apps you wrote? If not, don't bother eliminating class hierarchies, optimize your core logic instead.
Do your webapps spend most time waiting on database and microservices? See if you can eliminate or cache those, the wins are going to be much bigger than rewriting it in Rust.
Is your GraphQL compiler too slow? Unless you are FAANG with hundreds of thosands of developers and hundreds of people to spare, you will get much more bang-for-the-buck with some smart caching or just getting a bigger machine for CI jobs.
According to levels.fyi, the average senior SW engineer in San Francisco is $312k/year. With overhead, the actual cost is likely $500k/yer or so. There is _a lot_ of servers you can buy for that money before you can justify maintaining your own custom version of the existing software solution.
> The argument is not that performance optimization does not matter at all, but rather than low-level performance optimization, like rewriting compilers, writing your own custom storage system, or rewriting it in unreadable speed-optimized C++ is worth it.
People use these excuses for all kinds of performance arguments besides low-level/etc.
> You don't need to do a deep analysis to tell if optimization is needed or not, it is enough to assume best-case improvements and compare it to your FTE + overhead cost.
Sure, my point is people haven't even done rough math of FTE + overhead cost or even best-case improvements while still making those claims.
---
Less w.r.t. the article and more w.r.t. li4ick's comment. I've found numerous 10x gains in performance just by swapping an O(N^2) with an O(N) one (typically converting code using a List to using a Set instead). That doesn't cost 312k and if the original author was more concerned with performance they wouldn't've done things that way.
In some sectors software quality truly does not matter beyond a certain point (and the bar is really low). The customer very rarely has the resources or the time to try all the alternatives, especially if switching afterwards is expensive so if your marketing is good and your product works and has the needed features, you get sales, and if it's not, you don't.
Is it terrible that the app takes minutes to add a few thousand numbers? Of course it is. But it does not matter, the customer is used to software being terrible so he won't waste the time and money to switch to another software that is probably also terrible.
