The Google Blog posted an entry today revealing a feature that helps users get to their search results faster. It takes advantage of a feature that is present in the Firefox and Mozilla browsers. You can read more about how prefetching works on the Mozilla website.
This is a feature that is really handy but, like many technologies, can easily be abused. As a developer or designer you must weigh each use of prefetching to see if the benefit to your users outweighs any potential problems. ‘What problems’ you may ask? You are automatically downloading a page to the users browser cache without the user taking a direct action. This risks placing material on their machine that they did not want and are unaware of. If the material on the prefetched page is at all sensitive, private, or perhaps objectionable you may want to reconsider your use of this feature.
You are also taking up a user’s bandwidth without their implicit request or knowledge. This may not be an issue for a typical user, but what about those that are paying for their bandwidth by the kilobyte? Users with some dial-up connections or on mobile devices may be paying extra for downloading web pages they will never see.
In Google’s case they are not using this with every search result, only the top results that you are most likely to click on anyway. I think that the faster operation in this case generally outweighs any possible drawbacks. But just becuase Google is using it doesn’t mean it is a good idea in every situation. Please try to show some restraint, good judgement, and respect for your site’s visitors when choosing to prefetch pages.