Page speed has always been a factor in web design. Today, it is not only a factor in good design but also good Search Engine Optimization. Both factors are important to creating a good user experience. Ten to fifteen years ago, before high-speed Internet connections were commonplace there was a 30 second rule that good designers lived by; if a page took longer than 30 seconds to load it was too big. With the advancement of graphics design programs creating smaller and smaller file sizes, high-speed Internet and faster computers the average person has increased expectations and if a page does not load in 5-10 seconds they are more likely to click back and pick the next page in the search results list.
Google (who maintains a 65% share of the search engine market), has now incorporated page speed into their search algorithm for determining page rank and position. Page rank (the importance of a page relative to the rest of the Web) is the culmination of many factors and is a key component in determining the overall position of a web page in search results. Read More

