Why does C# compiler create private DisplayClass when using LINQ method Any() and how can I avoid it?

Question

I have this code (the whole code is not important but can be seen on this link):

internal static class PlayCardActionValidator
{
    public static bool CanPlayCard(...)
    {
        // ...
        var hasBigger =
            playerCards.Any(
                c => c.Suit == otherPlayerCard.Suit
                     && c.GetValue() > otherPlayerCard.GetValue());
        // ...
    }
}

After opening the code in decompiler (ILSpy) for example I noticed the existence of newly created class <>c__DisplayClass0_0 by the C# compiler:

This wouldn't be a problem for me if this code wasn't critical for the performance of the system. This method is called millions of times and the garbage collector is cleaning these <>c__DisplayClass0_0 instances which slows down the performance:

How can I avoid creating this class (his instances and their garbage collecting) when using the Any method?

Why does the C# compiler create this class and is there any alternative of Any() I can use?

Answer 1

To understand the "display class" you have to understand closures. The lambda you pass here is a closure, a special type of method that magically drags in state from the scope of the method it's in and "closes around" it.

...except of course that there's no such thing as magic. All that state has to actually live somewhere real, somewhere that's associated with the closure method and readily available from it. And what do you call the programming pattern where you associate state directly with one or more methods?

That's right: classes. The compiler transforms the lambda into a closure class, then instantiates the class inside the hosting method so the hosting method can access the state in the class.

The only way to not have this happen is to not use closures. If this is really impacting performance, use an old-school FOR loop instead of a LINQ expression.