Why Is My Computer Running Slow

I use Gmail, but for the past week or so it runs extremely slow, freezes, has a long typing delay etc. At first I thought it was just Gmail because every other website on my computer works normally, but today I discovered Gmail runs just fine on another computer. Could there be something on my computer causing just Gmail to run slow? I defragmented, but it didn’t fix anything. Other websites work fine, just not Gmail.

My computer is running slow and sticky when I’m online. It’s mostly Facebook and the apps are really bad. Ran Norton (I know isn’t a favorite of most computer geeks, but it’s what I got), and it didn’t pick up anything. Suggestions?