If it takes less than 1/2 a second it's fast enough. If it takes more than 10 seconds it is too slow. Within the realm of general computing tasks it doesn't matter what it is. Doesn't mean you can speed it up of course - some things just take the time they are going take. But if you are waiting for it, it's too slow and otherwise it's fast enough. :)

Used to be that computers were slower than they are now and to get acceptable performance you had to do tricky stuff of many more types of it than you do now. Some people are still stuck in that pattern of thought.

As others have said or implied in this thread, there is great virtue in providing an idiomatic solution to a common problam so that a "nearly best" solution just flows off the finger tips. If performance is measured in "time to solution", then time writing the code to find the solution is a component too - lazyness counts for a lot and idiomatic code is very often a nice compromise between programmer and execution performance.

Keep those performance questions coming.