It's a common programming thing - you write your code, it compiles, it runs, it runs properly on your test case, you try it on your full data, it's too slow. Yo

It's a common programming thing - you write your code, it compiles, it runs, it runs properly on your test case, you try it on your full data, it's too slow. You run your profiler and you spot some problems, you solve them, it's still too slow, repeat until fast enough, declare victory.