3 ms·

The slowest thing CPUs do by far is access memory. I don't see any possibly way that, for the given example, using more memory would ever be faster. At best 3*N

The slowest thing CPUs do by far is access memory. I don't see any possibly way that, for the given example, using more memory would ever be faster. At best 3*N all fits in cache and it's not as bad, but even then it's still at least one more cache miss which means it will still be slower even if it's not by much. Temporary memory is the worst type of memory. It's cache misses & pipeline stalls for no point. "Premature optimization" is not an excuse to write obviously bad code. Fixing this simple thing now is much faster, and simpler, than digging a big hole, jumping in it, and then hoping you can find something to pull yourself back out later. In the same way it's important to scatter about asserts and verify parameter arguments do in fact conform to the documented contract, it's also important to always keep an eye out for openly wasteful code.

davedx 7y ago
> it's also important to always keep an eye out for openly wasteful code. No, that's the point. It's really not. If your "openly wasteful code" does its job well and is readable and maintainable, it DOES NOT MATTER that it is "wasteful". If, on the other hand, the wasteful code causes your program to execute in 60 minutes instead of 10 seconds every time you run it, then it does matter and you should optimize it. Why is this such a difficult concept?
- kllrnohj 7y ago
  If you're trying to use Knuth's quote from 1974 as your justification for that concept then you've misunderstood his argument and should read the full thing, not the single phrase. This article is not advocating premature optimization as Knuth was discussing nor does the article's advice result in the evil that Knuth was warning against. If you have some other evidence or paper justifying why we can ignore obvious inefficiencies please provide a source. That's a rather radical claim to make, though, which may be why you find people struggle with the concept.
- deleted 7y ago
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davedx 7y ago

> it's also important to always keep an eye out for openly wasteful code. No, that's the point. It's really not. If your "openly wasteful code" does its job well and is readable and maintainable, it DOES NOT MATTER that it is "wasteful". If, on the other hand, the wasteful code causes your program to execute in 60 minutes instead of 10 seconds every time you run it, then it does matter and you should optimize it. Why is this such a difficult concept?

kllrnohj 7y ago
If you're trying to use Knuth's quote from 1974 as your justification for that concept then you've misunderstood his argument and should read the full thing, not the single phrase. This article is not advocating premature optimization as Knuth was discussing nor does the article's advice result in the evil that Knuth was warning against. If you have some other evidence or paper justifying why we can ignore obvious inefficiencies please provide a source. That's a rather radical claim to make, though, which may be why you find people struggle with the concept.
deleted 7y ago
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