Internet slowing down, requiring you to Press F5 several times to refresh a web page is one of the irritating thing a computer user can come across. It needs to be fixed asap.
Like previous versions, users have experienced internet going slow on Windows 8 too. If you think the slow speed is not because of service provider, you need to tweak Windows 8 in order to revive the connection speed.
To help you out on this issue, here is a useful video explaining how you can speed up your internet connection in Windows 8.