The odd thing is this behaviour is documented. Classes reference types, are always heap allocated, and passed by reference. Structs are value types, allocated i

The odd thing is this behaviour is documented. Classes reference types, are always heap allocated, and passed by reference. Structs are value types, allocated inline (that is inline in the containing object/array, or on the stack for local variables), and passed by value. Allocation time is going to be around the same for both types due to the GC, but there are performance implications depending on what you do later. In particular you can avoid garbage collection with appropriate use of structs but pass by value can mitigate those improvements.