Question

Is there a big performace difference between these 2 sample method calls ?

SampleClass sc = new SampleLib.SampleClass();
sc.DoSomething("Hello");

dynamic dyn = someAssembly.CreateInstance("SampleLib.SampleClass")
dyn.DoSomething("Hello");

Lets assume that

dynamic dyn =
someAssembly.CreateInstance(“SampleLib.SampleClass”)

is not frequent call. Once it creates the instance it will continue intensivly work only with created instance.

Answer 1

The only way to know for sure is to profile in your context. To set expectation, dynamic is pretty smart, and caches (per pattern) the actual code-path. As such, it is much faster than raw reflection, however an interface should be slightly faster and has the advantage of static checking.

Personally, I’d code to an interface from a library dll that both the current code and SampleLib can reference, i.e.

IMyInterface foo = (IMyInterface)someAssembly.CreateInstance(
                         "SampleLib.SampleClass");
...
foo.DoSomething("Hello");