Have you cleaned your internet buildup.
Download Ccleaner, its easy and cleans in two easy steps. The download is off to the right at the top of the green box.
Click on Download Latest Version. After you install you just hit Analyze
and when its done Run Cleaner
It may take a while to run if you haven't been cleaning your files. This will empty your Recycle bin also, so be sure you want that emptied. http://www.filehippo.com/download_ccleaner/
Do you have your Phishing Filter turned on? You may want to test it while it is turned off and see if there is a difference.
I have noticed that it has slowed a few people down quite a bit.
Open IE, go to the Tools option in the far right, bottom toolbar. Put your mouse over Phishing filter and see if it says to Turn it off or on. It it says Off then you know it is on, you can select to turn it off and see if this is your problem.
If it isn't, you can go back and turn it on again.