You want to know when it’s appropriate to inherit from MarshalByRefObject.
Don’t inherit a new type from MarshalByRefObject or from types that derive from it. The only reason to do it is if you intend to use the type’s extra features.
It takes longer to instantiate types that derive from MarshalByRefObject. The JIT compiler can’t inline methods from these types, so method calls execute slower. A good recommendation is to split complex objects into two distinct types. Have one type expose the methods that don’t need features from MarshalByRefObject. This way, the JIT compiler can optimize calls to the object’s methods.