The above comments are all 100% correct.

MY point simply is that too many people thing that

O(1) <= O(n) <= O(nLogn) < O(n^2) < O(n^3)

This in fact has NO actual basis in fact. I have seen many O(n^2) that are so much simpler than an O(nLogn) that for all reasonable values of n, the higher order of complexity is much faster.

Yet people persist in making comments about "efficiency" in terms of "big-O".