Pros and cons using two applications

[eluser]yoX64[/eluser]
Okay, but if I use two applications it affects the performance or it has some downsides? Because the way I see it, the admin is an "island" with stuff on it and the client side is another "island" with stuff on it; and there are bridges between them. I mean, I think that using two applications the whole CMS is better organized for future developers.