Everybody is familiar with the traditional game of SEO (Search Engine Optimization). First, you do keyword research, then write a post, create some backlinks, and finally pray that Google becomes aware of your existence. It seems like a drive with a map and hoping you wouldn't get missed at any point.
As soon as a Google user clicks to your website a clock starts to tick. If your site is slow or the text keeps moving while the user is reading or the button response at the other end is slow, then the user leaves your site. A single, irritated pressing of the "back" button means you lose traffic, interaction, and possibly even sales.