I'm running IE7 on Windows XP SP2. Lately I've noticed a slowdown when opening my browser and loading webpages. I've been running all types of spyware apps without a fix.
(I have Norton 360 running on my system.)

Before finding my fix I ran the following to eliminate any spyware and registry issues
- Spybot 1.6 (kill spyware)
- XP Repair Pro 2007 (clean registry)
- cwshredder (remove any coolweb issues)

Run 1 Internet explorer window (i.e. kill all other sessions).
In Internet Explorer I did the following
1) Tools > Internet Options > Advance > Browsing > uncheck enable third-party browser extensions.
2) Tools > Internet Options > General > Accesibility > uncheck Format documents using my style sheets.

Apply the above settings then close your browser and reopen. My browser now runs perfectly. I notice that my 'Norton's Phishing filter' toolbar has now dissapeared.

I hope this works for you.
regards