Adapted from a message from the California Digital Library
Web accelerators are applications that use various techniques to make web pages load faster or to download links, images, or files more quickly. Google Web Accelerator and the Firefox "DownThemAll" plugin are two commonly used products. The use of web accelerators can be a great convenience.
You should be aware of the potential problems caused by web accelerator use:
You may not be able to access licensed content from a valid UC IP address.
If you're using the Google Web Accelerator and the vendor displays a message such as "You do not have access to this resource from your current location," this is happening because the vendor is seeing a Google IP address rather than your UCB user's IP address. Try adding the vendor's domain (for example, ".jstor.org") to the "Don't Accelerate These Sites" text area in Google's Web Accelerator Preferences section. (For more information)
Triggering of vendor "excessive downloading" thresholds can result in your IP address being blocked by the vendor. This can be especially problematic if you're accessing the vendor's content via the proxy server or VPN (Virtual Private Network) service, and sharing a limited number of IP addresses with other users.