Quite some time ago I was asked to cover a C# developer interview for one of my neighbouring teams, and on the sheet of questions the original interviewer wanted me to ask was this question:
Q. Why should you NEVER use delegates?
I thought: “Well, at least I can rule myself out for the role!”
To my mind, if using delegates complicates your code or make it less readable/maintainable then you shouldn’t use it, but to say NEVER to using delegates? It just doesn’t make sense…
Puzzled, I asked: “Why not?”
“Because it’s an order of magnitude slower than using methods”
Sounds like he’s had his fingers burnt in the past, but still, it goes against everything I have experienced with using delegates..
“At least it is in the case of .Net 1.1”
Ahh, a little more context makes it that much more believable! But mind you, this was 2009 and .Net 3.5 had been out and surely whatever performance issue with delegates would have been fixed long along…
So, some two years later, I decided to put together a quick test to see if there is any difference in performance between invoking a delegate and a method in C# 4. The test is simple, given an empty delegate and method (see below), invoking each 10000 times in a row, which would take longer?
It’s worth noting that the test code is run in a debug, non-optimized (so no compiler in-lining) build.
Somewhat surprisingly, invoking delegates proved to be faster, averaging 269 ticks over 5 runs, where as invoking methods took an average of 365 ticks!