[Arnt]

I've used both in production. They both fast enough that their performance won't be your bottleneck. One's probably faster than the other by some percentage, but whatever you do, you're going to have some other problem that's bigger than that percentage.

At that point, talking about metrics is likely procrastination.

[cortesoft]

I don't think your experience alone is enough to say whether performance differences are significant or not.

While in your experience the performance differences were negligible, but that doesn't mean that will hold true in all usage scenarios. For example, maybe they perform similarly when caching many small files, but one struggles with serving longer running requests.

[Arnt]

Oh, sure. And one will be faster than the other in any given scenario. Not "faster like c++ is faster than ruby", though, it's "faster like this c++ compiler is faster than that one".

[nolok]

I'm sorry but I strongly disagree with the line of thought there.

Parent above was saying "both are at the same speed / none offer any speed advantage".

He is then asked for any metrics to support that statement, which is not an extravagant request and should be encouraged more.

Your answer that "At that point, talking about metrics is likely procrastination" and "one will be faster than the other in any given scenario" serves nothing other that further his statement while deriding the need for said metrics to prove that this is not turning anecdotal evidence into facts, and frankly serves nothing to the discussion short of saying the point should be accepted without verification and that asking for verification is useless.

A point of view I really cannot agree with. I do not know which is faster, nor if any of them is faster than the other or not, but if somebody claims one way or the other in a factual manner, he should not find it a waste of time to find an actual metric that shows it.

[Arnt]

OK, maybe I put that stupidly. Let me try it differently. "I've deployed both, I did enough load testing to learn something about their performance in the configurations that mattered to me, and the performance is so okay that I'm not even going to look it up. Choose based on other criteria."

There are other criteria.