How would you make this switch statement as fast as possible?

Question

2009-12-04 UPDATE: For profiling results on a number of the suggestions posted here, see below!

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The Question

Consider the following very

Answer 1

I'd extrapolate tster's reply to "switch over a custom hash function", assuming that the code generator creates a lookup table, or - failing that - building the lookup table myself.

The custom hash function should be simple, e.g.:

(int)ActivCode[0]*2 + ActivCode.Length-1

This would require a table of 51 elements, easily kept in L1 cache, under the following assumptions:

• Input data must already be validated
• empty string must be handled sepsarately
• no two-character-codes start with the same character
• adding new cases is hard

the empty string case could be incorporated if you could use an unsafe access to ActivCode[0] yielding the '\0' terminator.

Answer 2

I'd use a dictionary for the key value pairs and take advantage of the O(1) lookup time.

Answer 3

+1 for using a dictionary. Not necessarily for optimization, but it'd be cleaner.

I would probably use constants for the strings as well, though i doubt that'd buy you anything performance wise.