Google is making the change if incorporating the landing page loading time into the quality score to try to filter out the ads that effect the user experience.

In most cases this is to try to stop the ads that go through multiple URLs before it gets to displaying the landing page. These redirects can cause an extended delays which Google is trying to stop.

Most AdWords advertisers don’t have much to worry about with this change.

But sure if your site is slow to respond, or the pages take ages to load, this could be an indication that you need to make some performance tweaks to your site.