Data from major Internet providers like Google, Amazon and Akamai has shown that how fast a website loads significantly affects user behavior. And because users don’t like slow sites, Google uses load time as a factor in computing PageRank results. In short: It pays to be fast.
There are a lot of factors that can affect your site’s performance. While some are dependent on your hosting environment, there are plenty of factors beyond server/internet speed (and the obvious sheer number of bits to be loaded) that affect your page load time, such as HTTP connections, DNS lookups, and asset load sequencing.