I've heard the same thing, and my setup indeed includes a wireless keyboard and touchpad. But the weirhd thing is that i don't think i experienced thoses issues with the previous os version.

I also read somewhere it was related to Handover protocol using the same bandwidth as wifi. This sounds more plausible. Then having bluetooth + regular wifi + Handover wifi is too much and the connexion suffers. I which case there's not much Apple can do unfortunately, except rethink the whole stuff.

I'd say in any case the future in that matter doesn't look bright.