Which would contribute to a higher Quality Score for a display ad?
- High number of impressions
- Fast landing-page load time
- Testing all image ad sizes
- High maximum cost-per-clicks (CPCs)
Speed is important. Make sure your landing page loads quickly once someone clicks on your ad, whether on a computer or mobile device. In general, you have 3 seconds to turn your visitors into customers. Landing page loading time is also an important factor calculating Quality score. Not only on Display network.
Your landing page experience affects not only your Quality Score, but also your Ad Rank and advertising costs.
Read more here: https://support.google.com/adwords/answer/2404197?hl=en