Both the List.Exists method and IEnumerable.Any method can be used to find the first element that satisfies a predicate
in a collection. However, List.Exists can be faster than IEnumerable.Any for List objects, as well as requires
significantly less memory. For small collections, the performance difference may be negligible, but for large collections, it can be noticeable. The
same applies to ImmutableList and arrays too.
It is important to enable this rule with caution, as performance outcomes can vary significantly across different runtimes. Notably, the performance improvements in .NET 9 have brought
Any closer to the performance of collection-specific Exists methods in most scenarios.
Applies to
What is the potential impact?
We measured at least 3x improvement in execution time. For more details see the Benchmarks section from the More info
tab.
Also, no memory allocations were needed for the Exists method, since the search is done in-place.
Exceptions
Since LINQ to
Entities relies a lot on System.Linq for query conversion,
this rule won’t raise when used within LINQ to Entities syntaxes.
