|You could have malware on your system and McAfee (as well as Norton) are well known, but are not as good as the hype and can even slow down a good computer themselves.As a second possibility, you may have McAfee firewall as well as Windows Firewall both activated and this could cause very slow internet.|
First, install, update, and run Malwarebytes and remove completely all it finds.
Then either remove McAfee and install Avast (free version) or Webroot (free trial only) Secure Anywhere (good discounts for 3 or 5 machines and very light on system resources), or at least disable the McAfee Firewall and make sure that the Windows Firewall is active and see if that helps.
Finally, do a Disk Clean up and clean out your browser's Cookies, History, Temp Internet Files, etc.. I also recommend setting your browser to delete cookies when closing and reset it to keep history for only 2 or 3 days.
You have to be a little bit crazy to keep you from going insane.