Comment by tialaramex

Yeah, naive application of big-O complexity models can lead you far astray when you have real world problems. If you can do F in n*k1 time, but I need n*n*k2 time you may think your algorithm for F is better, O(n) compared to O(n squared) but if k1 is 1 second while k2 is 80 nanoseconds then actually my "worse" algorithm is faster until n is so huge that we have runtimes of about half a year.