Fastest Way to do Shallow Copy in C#

This is a complex subject with lots of possible solutions and many pros and cons to each. There is a wonderful article here that outlines several different ways of making a copy in C#. To summarize:

1. Clone Manually
   Tedious, but high level of control.

2. Clone with MemberwiseClone
   Only creates a shallow copy, i.e. for reference-type fields the original object and its clone refer to the same object.

3. Clone with Reflection
   Shallow copy by default, can be re-written to do deep copy. Advantage: automated. Disadvantage: reflection is slow.

4. Clone with Serialization
   Easy, automated. Give up some control and serialization is slowest of all.

5. Clone with IL, Clone with Extension Methods
   More advanced solutions, not as common.