Sadly, there is not enough data to confirm or deny any hypotheses as of now. May be that the low fps is causes due to slow CPU, while it is not noticeable on higher end machines, there are many factors that can contribute to lower fps and the cause may be the addon itself, yet I kind of suspect some other addon maybe in conjunction with Carbonite, that causes this.
Simply disable all addons and run only Carbonite then see if the fps is really that low because of it or not.
