Cubase 6.5/ reason 6 Rewire cpu problem

Hi, I’m getting massive CPU spikes when I rewire reason through cubase with these new versions. Reason’s never even dented cpu before - is anyone else experiencing this… and does anyone know anything I can do about it. It’s making using the two programs together unusable, which is a nightmare for me as it’s the way I’m used to working.
Thanks
Nick