Recently I switched my ISP from AT&T DSL (I know … what was I thinking) back to Comcast. The process went thru very quick and in 30 minutes my old cable modem was hooked up and provisioned and was seeing 23 Mb/s speeds. with 11ms response time.
But… wait. As soon as I started using it I realized that a lot of web pages were taking forever to load and I quickly remembered the old Comcast issue. Unreliable/slow DNS servers. And you need the DNS response before you can actually start HTTP transfer and see the page.
There are a lot of free name servers so I will list a few:
OpenDNS: 184.108.40.206, 220.127.116.11 (my choice)
AT&T and Level 3: 18.104.22.168, 22.214.171.124, 126.96.36.199
Google :188.8.131.52, 184.108.40.206
I would recommend to set the Primary and Secondary from 2 different groups and make these changes on your router so any connected device will inherit the changes.
Problem solved. Happy browsing!