I just had my TV installed and have experienced this problem. Google pointed me to this thread, and so have promptly disabled Youview.
The TV is now incredibly fast without it. The guide button response time is almost instant, compared to taking, I would say, around five seconds before. I know that might not sound like much written down, but in terms of response time for the most basic of requests, from a local device, it's terrible. A chore to use and a relief when it works better.
Every time I pressed guide, I would sit there waiting, wondering whether it had been registered. So then, I'd press it again, only for it to slowly start loading up. And this affects the response time of the other functions, like home and discover. All are much slower with Youview enabled.
I also prefer the in-built Sony guide: a seamless design with more channels, due less wasted space. Youview may have two week functionality, but I don't need that cryptically advertised across a third of the screen every time I use the basic guide. They should either make the utility more explicit than merely highlighting today’s date, or they integrate it more subtley, for use when needed. It's the kind of thing you usually know you want before you open the guide, and are prepared to invest time fidling around for; it's not something that you need drawn to your attention otherwise.
So I would advise anyone who has purchased one of these TVs to disable Youview and try the inbuilt guide, since it takes less than a minute to re-enable Youview again in settings. This advice is especially for anyone who either, or neither, knows nor cares what Youview is.
