google designs its products with user experience as the number one priority. Early in google‘s history, our founders, Larry and Sergey, articulated this philosophy in Ten things Google has found to be true. One of these principles is “Fast is better than slow.” We’ve found this rule to be especially applicable to the landing pages of adwords ads. When a user clicks an ad, a landing page that loads quickly provides a better user experience than a landing page that loads slowly.

In early March, we announced that we’d soon incorporate an additional factor into Quality Score, namely landing page load time — where load time is defined as the amount of time it takes for a user to see the landing page after clicking an ad. In early May we announced that landing page load time information had become available on the Keyword Analysis page.

Starting today, this load time factor will be incorporated into your keywords’ Quality Scores. Keywords with landing pages that load slowly may get lower Quality Scores (and thus higher minimum bids). Conversely, keywords with landing pages that load very quickly may get higher Quality Scores and lower minimum bids.

Why are we doing this?
Two reasons: First, users have the best experience when they don’t have to wait a long time for landing pages to load. Interstitial pages, multiple redirects, excessively slow servers, and other things that can increase load times only keep users from getting what they want: information about your business. Second, users are more likely to abandon landing pages that load slowly, which can hurt your conversion rate.

How can I improve my load time?
The adwords system re-evaluates landing pages on a regular basis. If you make significant improvements to your landing page’s load time, you should see a better Quality Score and lower minimum cost-per-click (CPC) bids. Note that your Quality Score may change/increase gradually over a number of weeks after you improve your load time.

To learn more about load time and landing page quality, please see this article in the adwords Help Center.

Full article : http://adwords.blogspot.com/2008/06/landing-page-load-time-now-affects.html