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.
Maybe I'm misreading your point here, but it very much matters what it is. If your processing data that arrives daily, 10 seconds is not too slow. If your processing data that is arriving every 1/4 of a second, 1/2 second isn't fast enough.
Without knowing what it is, its impossible to say whether performance is a problem or not.