Could be something as simple as adware. Run spybot, Malaware, or Ad-Aware, and clean that up.
It may also be time to add some ram. As more and more content gets dumped onto websites, you will be slower and slower. At a minimum, you probably want 2G of ram,
Are you running XP, vista, or windows 7?
If you are running xp, the easy way to check for ram is:
-left click "start"
-right click "my computer"
-left click "properties" and under the "general" tab, you should see the amount of RAM, near the bottom. Your computer won't likely recognize more than 4G of ram, so don't blow your money. RAM cards for laptops should be installed in sets of equal ram. eg- if you have two 256MB cards, it will show up as 512 RAM. If you want to upgrade, you will not buy one 2G card to install beside one of the two existing 256MB cards. Instead, if you want 2G of RAM, you would install two 1G cards, and give your other RAM away to someone else. At the most, you would install two 2G cards, giving a total of 4G, but remember that your computer will show somewhere between 3G-3.8G. You should be able to buy RAM fairly cheap for lap tops. You can google your brand and model computer (look on bottom) with "ram" and find online sources which will show you the specs on what you need. EdgeTech is a good source with great prices. Install is easy, and you should be able to see videos online for how to install.