Set up lots of live tiles on the Start screen and you could find they’re using a lot of network bandwidth, which could perhaps become a problem if you’re running a slow or metered connection. But Windows 8 does offer one option that might help.
Click your network connection on the taskbar (or the Start Screen Charms bar), right-click your network connection in the list and select “Set as metered connection” (you’ll only see this with wireless adaptors). Windows will then limit what individual live tiles can do, while also downloading only priority Windows updates, and applying a few other restrictions. Right-click the connection again and select “Set as unmetered” to change it back.