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

Use the length of the code to create a unique value from that code instead of using GetHashCode() . It turns out there are no collisions if you use the first letter of the code shifted by the length of the code. This reduces the cost to two comparisons, one array index and one shift (on average).

public static MarketDataExchange GetMarketDataExchange(string ActivCode)
{
    if (ActivCode == null)
        return MarketDataExchange.NONE;
    if (ActivCode.Length == 0)
        return MarketDataExchange.NBBO;
    return (MarketDataExchange)((ActivCode[0] << ActivCode.Length));
}

public enum MarketDataExchange
{
    NONE = 0,
    NBBO = 1,
    AMEX = ('A'<<1),
    BSE = ('B'<<1),
    BATS = ('B'<<2),
    NSE = ('C'<<1),
    CHX = ('M'<<2),
    NYSE = ('N'<<1),
    ARCA = ('P'<<2),
    NASDAQ = ('Q'<<1),
    NASDAQ_ADF = ('Q'<<2),
    CBOE = ('W'<<1),
    PHLX = ('X'<<1),
    DIRECTEDGE = ('Y'<<1),
}