Re:The computers are fast, but you don't know it
by jerf on Thursday June 16, 2022 @10:07PM
(#31773348)
Languages top out at around 50x, and that's the extreme of pure CPython to C.
For as many factors of magnitude as I am talking about, you have to be screwing up algorithms, networks, and a whole bunch of other things too.
Python and similar languages like Ruby really do make it easy to accidentally pile things on top of each other, but you can screw up in pure assembler with enough work put into it. Assembler doesn't stop you from being accidentally quadratic or using networks in a silly way.
At least with Chrome's V8, the difference is not that big.
Sure, it loses to C/C++, because it can't vectorize and uses orders of magnitude more memory, but at least in the Computer Language Benchmarks Game it's "just" 2-4x slower.
I remember getting a faster program doing large matrix multiplication in JavaScript than in C with -o1, because V8 figured out that I'm reading from and writing to the same cell, so optimised that out, which gave it an edge, because in both cases the memory bandwidth limited the speed of execution.
As for Electron and the like: half of the reason why they're slow is that document reflows are not minimized, so the underlying view engine works really, really hard to re-render the same thing over and over again.
It's not nearly as visible in web apps, because these in turn are often slowed down by the HTTP connection limit(hardcoded to six in most browsers).