What are the hidden costs of LINQ closures in large-scale applications?

Closures introduce heap allocations, state retention, and potential memory leaks in long-lived queries.

When lambdas capture external variables, the compiler generates closure classes that allocate objects on the heap. In large-scale systems, repeated closures can increase GC pressure. Additionally, captured variables may unintentionally extend object lifetimes, leading to memory retention issues. In async or deferred LINQ pipelines, this becomes more pronounced as execution is delayed.