Shoutbox

As a general rule, skins do not make any speed difference. The do not slow down Messenger at all, not even a tiny bit, due to the way they are designed (load-when-needed system, no extra conversion in the middle, ...). The only thing you may notice is a second or maybe two of extra loading time when Messenger is started, but after that, it's a smooth ride.

As for making Messenger faster, I'd say no. The default interface of Messenger is pretty simple and does not make extensive use of big bitmaps. Removing a couple of buttons won't change anything in the loading time, you may speed things up a little bit in the contact list depending on what you do to the contact entries but even that, I doubt. The UI system of Messenger is pretty clever and very well done in my opinion, it's completely detached from the logic, that's why we can skin it and that's also why changing the layout of the window won't affect performances.