Macbook Pro 2012 Slow Internet

I bought a Macbook Pro (i7, 8 GB) about two years ago. It seems lately the intenet on it has become very, very slow. Often times it becomes completely unresponsive.

It seems to go through 10-15 minute periods where

1) internet is running really slow for any page I try to go to.

2) I can search for something on Google and when I click on the link, a blank page opens up with a google address for the URL.

3) If I can get to a web page, certain things like pictures, or sometimes banner ads will fail to load.

I mainly use Safari, but it happens with Firefox, too. My hard drive is well under half full. It doesn't feel like my computer is running slower overall.

I know its not our internet. My wife bought the same Macbook Pro with different specs (i5, 4 GB). I run our speed tests side by side and hers finishes with 50 MB/s while mine is stil pinging to find the best server for the test. Once completed, my test has somewhere between 5-10 MB/s.

I'm kind of at a loss for how to troubleshoot this. I downloaded Sophos Anti-Virus to see if I have anything to worry about there. Any other suggestions?