What is Google Instant? You can refer as below – It was taken from Google website,
Google Instant is a search enhancement that shows results as you type. We are pushing the limits of our technology and infrastructure to help you get better search results, faster. Our key technical insight was that people type slowly, but read quickly, typically taking 300 milliseconds between keystrokes, but only 30 milliseconds (a tenth of the time!) to glance at another part of the page. This means that you can scan a results page while you type.
If you want to disable this feature – head to this link, http://www.google.com/preferences. In this page, select the option Never show Instant results. Press Save to activate the change.