Macbook Pro Internet Issues

I have had my Macbook Pro (not retina) for 5 months. I ordered it from Apple in June, used it for web browsing in the summer, and now I use it for the majority of my homework workload for school. I take it to and from school 3 to 4 times a week (going from their wifi to mine each time). Over the past couple of weeks, my mac's internet speed has come to a near standstill. It can access my most used websites fast, but going to a website never used before, forget it. Nothing else seems to have slowed down. One thing that I have been thinking is that my school has a proxy network that I set up on my computer so that I can access our school databases from home. What could the problem be? What can I do to fix it?

You can setup different locations separately in your Network preferences. Create one location for when you're at school, another at home using the Proxy, and yet another at home or anywhere else with no proxy. Going through a Proxy will slow you down.