Google has protected its Instant Search feature since June 2004, when it filed a document titled "Anticipated query generation and processing in a search engine" (granted in November 2010). the company recently detailed the initial patent with a new filing that explains "predictive query completion and predictive search results" on a much deeper level than the initial patent does.
The patent application, which was submitted in August of 2011, describes a dynamic process in which the search query entered by a user is monitored and completed depending on the likelihood of input intentions. Dynamic search results are being displayed and changed depending on the predictive search query completion that is updated with every new letter that is entered by the user.
The document pays special attention to the "excessive bandwidth" a predictive search system requires. According to the patent, the technology is able to determine delay criteria and prioritizes them: "In some implementations, the search service can invoke different delay criteria for different clients based on the number of query suggestion requests received from respective clients, the number of prediction criteria met for respective clients, based on the time interval between consecutive query suggestion requests for a respective client, and/or based on the time interval between the determination of consecutive prediction criteria being met for a respective client."
Google also notes that the speed of serving search results can be "throttled" based on the quality of the data connection to the client. The higher the available bandwidth " the more aggressive the search service is in providing search results." The patent application also covers ad serving based on predictive search results, but does not include the feature of pre-rendering web pages in search results.