Performance of LINQ Any vs FirstOrDefault != null
c#, linq
Solution
The enumeration in `Any()` stops as soon as it finds a matching item as well:
https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.any
I would expect the performance to be very similar. Note that the `FirstOrDefault` version won't work with a collection of value types (since the default isn't null) but the `Any` version would.
Problem
There are multiple places in an Open Source Project (OSP) code I contribute, where it has to be determined if an element in a collection satisfies a certain condition. I've seen the use of LINQ expression `Any(lambda expression)` in some cases and `FirstOrDefault(lambda expression) != null` in others but never given a thought about it. I have reached now a point where I have to do some iterations to collections made from queries to a DB and want to optimize the runtime. So I figured that `FirstOrDefault(lambda expression) != null` should be faster than `Any(lambda expression)`,right? In the case of `FirstOrDefault(lambda expression) != null`, the iteration (probably) stops when it finds an element that satisfies the condition (worse case scenario it iterates through the entire collection and returns `null`). In the case of `Any(lambda expression)` I imagine that the iteration continues to the end of the collection even if an element that satisfies the condition is found. Edit: The above is not true as Jackson Pope mentioned and linked the related MSDN article. Are my thoughts correct or am I missing something?