Going to echo everyone here and say that I'm on Sky Unlimited as well and have had this unplayable lag since Monday. I've not written an e-mail highlighting it to Sky but will be now that I've seen this thread.

While the issues are ongoing, I've downloaded WTFast on a trial account as a bandaid fix and this has completely fixed my problem. I'd recommend anyone on Sky to both e-mail and call their Customer Support and give this program a shot.