Google Web Accelerator is a software that accelerates page load times. It prefetches some of the pages and uses Google servers to retrieve data faster.
If you have the program, you must be wondering if it's really working well. Google displays the amount of time Google Web Accelerator saved, but this is an aggregated value.
But there's a way to see how fast Google's accelerator is: go to this page, called Google Web Accelerator IFrame Racing (it works only if you have the software) and enter a URL. The upper iframe shows the optimized loading, while the other iframe shows the standard loading.
If you want to load a page directly, without the accelerator, add .direct.google after the domain name: instead of http://www.cnn.com type http://www.cnn.com.direct.google.