Often when I hear people complain about "tiny" improvements, I change the
context: "Ok, I'm going to raise your salary 5%, or is that too small and
you don't want it?" Suddenly that 5% looks pretty good.
To extend this analogy a bit, I think Neil's objection was more along the lines of "Why work an extra 5 hours a week for only a 5% raise?"
I don't think anyone's going to pooh-pooh a performance improvement. Neil's concern is just about whether the benefit justifies the cost.