alt Hacker News> I choose to use Python because I am productive with it.
That, I fully understand. I think many developers are productive in one language: in the one that they know best. Which is probably the one they use most. It might happen that this is is a "fast" language by accident (like Java or Go), or a language like Python. And then there is never enough reason to switch.
> "Most engineers would kill for a 5% speedup"
I think this is very rare - maybe a heavily used app in Facebook or Google, where 5% could mean a lot of money. But a factor of 10 speedup is much more common (and possible sometimes).
> there is an allure to performance optimization due to the fact that it can be so easily quantified.
That's true. I also think simplicity is quantifiable, and so my personal hobby is to write something impressive in few lines. Like a chess engine, QR code reader, editor, data compression tool, compiler, in 500 lines. But this is mostly for hobbies I guess. For work, it's mostly about features, and then performance, I guess.
> I think many developers are productive in one language: in the one that they know best.
While superficially true, this conflates cause and effect. I am, or was at one time, extremely proficient in multiple assembly languages, Fortran, C, Pascal, Modula-2, Verilog, and Python, marginally proficient in multiple other assembly languages, Perl, Tcl, etc., and have toyed with various lisps and functional programming languages.
I viscerally recoiled from a few languages, like Java, Javascript, and C++, and found other languages, like Go, Lua and Julia, not compelling enough to bother switching to for my use cases.
And while I can certainly believe that many people are most productive in the language they know best, that most emphatically doesn't mean that they learned a language and became proficient in it to the exclusion of others. It most certainly meant in my case that I spent more time with, and learned ever more about, a language that was already productive and useful for me.