Quit putting out bogus and false information. If you restore your phone before taking it in.....your warranty will not be void.
As for slowing down, that is not entirely true either. If you let winterboard do all of the work, then yes there is a slow down. I use winterboard only to wallpaper my springboard. I use diskaid to access the root directory to change everything else. If you go
here, there is a list of all the graphics locations. Physically change them instead of letting winterboard do it and you will notice no slow down. I change all of my icons "permanently" and therefore there is no slow down. You can change them back to default by restoring the phone. This prevents winterboard from "painting over" the stock icons.
You need to be more careful before you go spouting out bad info. Someone had the correct info and will usually flame you. If you don't want to JB, then don't but don't put out incorrect info to scare other people.
Custom themes slow down the springboard and the iphone overall. Also it will void your warrenty not worth it if you ask me.
