I have Windows 10, honestly I have never had anything wrong. Neither has any of my friends. I would run a few scans on your PC, check your firewalls, also check your processes to see what may be open that you've never seen before. Another good method is to go into control panel, and into the uninstall area. See what's been previously updated or even added. New firewall software should be looked at closely to see if it's from windows or such, or if there are any other weird applications that you've never seen before.
It could be a variation of a virus called "no access" which slowly blocks games, downloads, and other internet needed applications from working properly.
I have heard the rumors of various downloads of Windows 10 being hijacked by hackers and viruses, but I guess it's where you download it from, what the security on your PC is like, and other possible things. Basically, using precaution to ensure your PC is well protected.