Performance of using static methods vs instantiating the class containing the methods

Question

I'm working on a project in C#. The previous programmer didn't know object oriented programming, so most of the code is in huge files (we're talking around 4-5000 lines) spread over tens and sometimes hundreds of methods, but only one class. Refactoring such a project is a huge undertaking, and so I've semi-learned to live with it for now.

Whenever a method is used in one of the code files, the class is instantiated and then the method is called on the object instance.

I'm wondering whether there are any noticeable performance penalties in doing it this way? Should I make all the methods static "for now" and, most importantly, will the application benefit from it in any way?

Answer 1

From here, a static call is 4 to 5 times faster than constructing an instance every time you call an instance method. However, we're still only talking about tens of nanoseconds per call, so you're unlikely to notice any benefit unless you have really tight loops calling a method millions of times, and you could get the same benefit by constructing a single instance outside that loop and reusing it.

Since you'd have to change every call site to use the newly static method, you're probably better spending your time on gradually refactoring.

Answer 2

I have dealt with a similar problem where i work. The programmer before me created 1 controller class where all the BLL functions were dumped.

We are redesigning the system now and have created many Controller classes depending on what they are supposed to control e.g.

UserController, GeographyController, ShoppingController...

Inside each controller class they have static methods which make calls to cache or the DAL using the singleton pattern.

This has given us 2 main advantages. It is slightly faster(around 2-3 times faster but were talking nanoseconds here ;P). The other is that the code is much cleaner

i.e

ShoppingController.ListPaymentMethods() 

instead of

new ShoppingController().ListPaymentMethods() 

I think it makes sense to use static methods or classes if the class doesn't maintain any state.