The code tag is incredibly useful for the programming forums.
However one very big issue it has is that for each edit of your post, regardless of whether you touch its contents, the rendered contents inserts spaces ahead of random lines. This accumulates per edit to the point where the spacing is quite off and difficult to read.
Since this is a page render time bug, I can’t edit this as a user. If I edit my post the spacing looks correct. However that is not the case at render time.
See the following post for an example:
http://forums.cgsociety.org/showpost.php?p=7224110&postcount=5