Attn: Mozilla Users!
According to Google: "On some searches, Google automatically instructs your browser to start downloading the top search result before you click on it. If you click on top result, the destination page will load faster than before." The bad part is that your browser cache will fill up faster and if you are setup to automatically accept cookies, you'll get quite a few of those. Visit their site to learn more about this feature, plus get instructions on how to activate or deactivate it.