Great article by MarketingProfs (Larry Kim) on Google AdWords Quality Scores and your landing pages.

http://www.marketingprofs.com/articles/2011/4230/three-lesser-known-ways-to-enhance-adwords-quality-score?adref=nlt012111

Page load time not only affects your quality score, but it can dramatically impact page load times. I recently worked with someone who’s landing pages were loading in about 15-20 seconds! That has a major affect on user experience. Very few people with broadband will wait even 5 seconds for a page to load, let alone 20 seconds. We reduced the size and number of images, decreased the amount of and size of includes and modified the hosting and caching settings of the web server. The result was a page that loaded in about two seconds. What an improvement! Think of all the people that were leaving even before they saw the message.

Another very important aspect is to make sure that your landing page matches your keyword or keyword phrase. It’s good to have “H1” tags that have the keyword, as well as sub-headers and bullet points. These all improve the visual recognition among users that your page matches their query, and improves your quality score in the eyes of Google. I know it is a lot of work when you have a lot of keywords. I am working with someone who has 1000’s of keywords and yes, over 250 landing pages. They use a platform that makes building page variations easy and scalable. You might not need such tools, but that doesn’t excuse you from building pages that match your search terms.

Similarly your landing pages should visually match your display ads. Remember that your landing pages should be separate from your organic website, so you need not worry too much about SEO and duplicate content. Your landing pages are intended to support your paid traffic, not organic searches.