Optimizing Lookups: Dictionary key lookups vs. Array index lookups

Question

I\'m writing a 7 card poker hand evaluator as one of my pet projects. While trying to optimize its speed (I like the challenge), I was shocked to find that the performance o

Answer 1

Is this type of behavior expected (performance decrease by a factor of 8)?

Why not? Each array lookup is almost intantaneous/negligeable, whereas a dictionary lookup may need at least an extra subroutine call.

The point of their both being O(1) means that even if you have 50 times more items in each collection, the performance decrease is still only a factor of whatever it is (8).