C# – How create High Performance .NET classes using reflection


Ok, so we all know Reflecttion is many time less performant than "newing" a class instance, and in many cases this is just fine depending on the application requirements.

QUESTION: How can we create high performance .NET classes using a late binding (Reflection) strategy.

I have an existing requirement that demands class instances be created using reflection (CreateInstance), but performance is critical. In my situation I am creating instances for every incoming SMS Message in our application. During production this could easily be over a million per day.

I would like to hear and share some ideas on how to create .NET classes without directly referencing the classes in code, for example using Reflection. I was also thinking if there is a way to somehow cache a class Factory that can improve the "Creation" time

Best Solution

1 million a day is not a lot; I'd just use Activator.CreateInstance (a quick test using Activator.CreatInstance(Type) shows that on my lowly laptop it can create 1M objects from aType in ~2s).

Thoughts on creating objects quickly:

  • use generics and the : new() constraint (zero effort)
  • use DynamicMethod and write the IL (not hard)

An implementation of the new approach (without needing the : new() constraint externally) is shown here: ObjectFactory.cs.

For an IL example, see dapper-dot-net and il.Emit(OpCodes.Newobj, ...)