Why Is the Internet So Infuriatingly Slow?
I agree with you that optimizing the TCP stack and usage of bandwidth (ie not downloading ads, etc) could speed up internet use, but I am sorry to say that you must never have experienced a high bandwidth home internet connection from standard consumer grade products.
Even with non-optimized settings, high bandwidth doesn't happen if the infrastructure isn't there to support it. If 100 people are connected via a 10 Mbps line to a 100 Mbps backbone, there is going to be congestion. Especially when you factor in streaming video, P2P networks, online gaming, streaming music, etc. You could have the most optimized network in the world, but when you seriously oversell bandwidth not a thing you do other than increasing the backbone speed will help with slowdowns and congestion.