Why does LINQ performance degrade with multiple chained transformations?

Each LINQ operator adds iterator overhead and increases deferred execution complexity.

Every LINQ method like Where, Select, or OrderBy creates a new iterator layer. In IEnumerable, this results in a pipeline of nested MoveNext calls. Each layer adds function invocation overhead, increasing CPU usage. In IQueryable, multiple transformations may also produce more complex SQL, sometimes with redundant subqueries. This layered structure can degrade performance both in memory and database execution.