Google’s accelerator uses several tricks:

• Google servers cache common webpages and images. If somebody else using Google has recently examined a web page you want to look it, the Google accelerator will automatically fetch it from a fast Google cache server. This works on top of any caching your ISP or browser software does.
• Google servers deliver cached web pages in compressed format so they transmit faster.
• The Google accelerator preemptively requests pages it thinks you might want to look at in future, in the background, when it has nothing better to do.

Upside

• The benefit to you is you get faster Internet access.
• The benefit to Google is they get to see which pages everyone is using most. This will help them in their rankings and deciding how often to respider. This will lead to better quality lookup.
• The benefit to the Internet community is the entire Internet is used more efficiently, spending less and getting more value out of the same equipment.
• The upside of this to websites is that as traffic grows you don’t have to buy as many bigger servers. If people access your site through the Google accelerator, it is Google shouldering the bigger load.

Downside

• Beware. The Google web accelerator proxy drastically slows down Java Web start unless you configure jawaws.exe to use a direct network connection.
• The downside of this to you is Google gets to look over your shoulder at everything you do, including passwords, your pornography viewing habits and your political tastes. It is very big brotherish, but in principle nothing your ISP could not do.
• The downside of this to websites is that they will no longer get accurate hit counts. Google can fetch a page once and the feed its copy to 1000 people. If Google is not very careful, they will befuddle various affiliate click through programs, since clicks won’t register if they are served from cache.
• A major downside is that Google has implemented its beta accelerator only for Internet Explorer and Firefox. This could be the death knell for all other browsers if the Google Accelerator catches on. For other browsers running on Windows, you’ll need to manually configure your proxy settings to 127.0.0.1:9100 for HTTP connections. This not rocket science, but enough of a hassle to block the average user.
• If this catches on, it will make Google a monopoly.

Preparing To Use the Google Accelerator