Hello, I am using Avast Internet Security version 2014.9.0.2011 and that is slowing down my internet, especially when I’m watching videos. Even I cannot watch videos on youtube or etc. But if I stop web shield, I can. Which adjustment cause that? I couldn’t find for repairing.
What OS and browser are you using?
My OS is Windows 7 Ultimate 64 Bit and my browser is Chrome.
You might want to take a look at this sticky topic about download issues with the web shield and a possible solution.
Try disabling the “avast online security” plug-in first before you do anything too drastic.
You can disable the AOS by going to “tools” in each of your browsers. 
They doesn’t work :(.
I just used Avast’s own setup application for fix, and it’s done! Thaks for everyone to try to help me.
I am still having the same problem. I learned that the problem is the Firewall (not the web scanner).
Windows 7: 64bit
latest window and Avast