Why is LINQ .Where(predicate).First() faster than .First(predicate)?

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I got the same results: where+first was quicker than first.

As Jon noted, Linq uses lazy evaluation so the performance should be (and is) broadly similar for both methods.

Looking in Reflector, First uses a simple foreach loop to iterate through the collection but Where has a variety of iterators specialised for different collection types (arrays, lists, etc.). Presumably this is what gives Where the small advantage.

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