Hello,
If you've only just upgraded then Windows takes a small amount of time to index the drive, mess with .net libraries, plus a lot of other stuff. Depending on the version it also downloads the next version along with other updates. This process will slow web browsing so, as a suggestion, leave your computer idling while you watch TV, don't let it sleep, allowing it time to get stuff done.
Thanks.
P.s. What spec is your computer, how much hard drive space, do you have a whole heap of other stuff installed, what runs at start-up?