[jonahx]

It could be. And when I have evidence that user experience is affected, I'll care about the difference. But what if it's 1ms vs 3ms? Or 3ms vs 9ms? And the 9ms time is a much more expressive, productive, high-level language?

I'm not going to care about the difference just because "omg one number is 3x another number!?!"

[sharpneli]

For an soft realtime application like game that’s the difference between 10fps and 30fps. Or 30 and 90. Basically total failure or success.

[jonahx]

I was referring to response time in a GUI app -- 9ms is undetectable.

Again, if you have a reason the speed matters, then it matters. The specific numbers here are not relevant to my argument, which boils down to: being "slow", in and of itself, is meaningless.