this is the beginning of my dictation.
Your frustration is understandable. However, processor speed has little to do with Internet performance, even with intense online games. Modern computers have processing speeds that are more than 100 times faster than what is needed for playing a game over the Internet.
The fact that you have another computer with a different operating system that works very well would suggest that something has happened to your computer that you are not aware of. The most likely scenario is some kind of infection with spyware, adware or maybe a virus.
Nevertheless, it is very important you contact the manufacturer of your new computer and register a complaint with them. They might know a some issue they had with that particular model.
The only thing I can suggest at this point is a couple of things.
First, create a new user account and sign into that account and try logging into the Internet again.
Second, run the network wizard again in Windows and see if that helps. You have to reset your computer before the changes take place.
That's the best I can offer. Hopefully somebody else has an idea.