Is it because we should load class (by string for example), create instance, then search for appropriate method, pack parameters, and then just invoke method? S
As an addendum to Jon Skeet's answer above (I need more reputation in order to be able to comment.):
Reflection is dependent on CPU resources being available; if you have problem with your application being slow, reflection won't solve anything, just make it slower.
Like Java itself, reflection isn't slow any more - it is more of an old rumor ;)