Trash client?

Why is it that I can run 80-100 fps in game but when I get into champion select the client is so laggy I barely have time to ban/pick my champion? Just had a game where the music from queue was playing my entire match and it was very distracting as I couldnt turn it off or close my client without leaving the game. I've seen a lot of people say that they don't like this new client what do you guys think?