It isn't just something designers and marketers toss around, it's a fact that if your website is slow you're undoubtedly losing money. Think about it? If you're an incredibly patient person you've most certainly at one point in your life moaned at the thought of having to stand in a long waiting line. We get bored and at times angry at the thought of having to wait longer then expected. So why would this be any different when waiting for a website to load?
It doesn't seem like much but if your competitors website(s) are loading 3 to 5 seconds faster then your own there's going to be customers who are opting to skip the line and movie onto a much shorter one. There are a handful of reasons as to why people will leave your website and page speed is one of the first.
There is no secret that Google thinks site speed is important. It isn't breaking news and for the most part the search engine giant has always rewarded sites with clean code, compressed images, and faster response times. In 2011 they couldn't have made it anymore obvious:
At Google, we’re striving to make the whole web fast. As part of that effort, we’re launching a new web-based tool in Google Labs, Page Speed Online, which analyzes the performance of web pages and gives specific suggestions for making them faster. Page Speed Online is available from any browser, at any time. This allows website owners to get immediate access to Page Speed performance suggestions so they can make their pages faster.
As an SEO company improving page speed is an important part of the overall picture but truth be told it isn't going to improve your search rankings to the point where it jumps 50 spots in the ranking. With any new site the most important thing to look for is providing a user friendly experience while maintaining proper on site techniques, clean code, and proper interlinking. It's been long rumoured that Google uses up to 200 (or more) ranking factors when determining the position of a website and pagespeed plays a very small percentage in that.