type-design-performance

To optimize .NET type design for performance, seal classes by default to enable JIT devirtualization, use readonly structs to avoid defensive copies, and prefer static pure functions to minimize state and reduce allocations.

Sealing classes improves C# performance by enabling JIT devirtualization, which removes the overhead of virtual method dispatch, while also clarifying intended extension points and reducing memory footprints in performance-sensitive code.

The best way to avoid allocations in .NET library internals is deferring enumeration, choosing appropriate immutable collection types, and applying static pure functions to minimize state and memory footprints.

You need readonly structs in C# architecture when designing immutable value types, which prevents the compiler from generating costly defensive copies during method calls in performance-critical components.

Using static pure functions improves API design maintainability by minimizing state, improving testability, and reducing allocations, which collectively solve performance pitfalls and create efficient, maintainable .NET types.

Deferring enumeration in .NET collection types requires careful lifecycle management to avoid multiple evaluations, but when applied correctly it minimizes allocation timing costs and optimizes performance-sensitive API surfaces.