There have been rumours around since November last year that Google either were already or were about to include the speed of your website as a criteria in their ranking algorithm.

A blog post Google fellow Amit Singhal and principal engineer Matt Cutts from the 9^th April now confirms that this is the case with the post stating that "Speeding up websites is important -- not just to site owners, but to all Internet users. Faster sites create happy users and we've seen in our internal studies that when a site responds slowly, visitors spend less time there"

Website owners now have another incentive to make sure that their sites perform at an acceptable level. A survey conducted by Forrester Consulting at the end of 2009 to examine eCommerce web site performance and its correlation with an on-line shopper's behaviour confirms Google's view . The most compelling results reveal that two seconds is the new threshold in terms of an average on-line shopper's expectation for a web page to load and 40 percent of shoppers will wait no more than three seconds before abandoning a retail or travel site.

Additional findings indicate that quick page loading is a key factor in a consumer's loyalty to an eCommerce site, especially for high spenders. 79 percent of on-line shoppers who experience a dissatisfying visit are less likely to buy from the same site again while 27 percent are less likely to buy from the same site's physical store, suggesting that the impact of a bad on-line experience will reach beyond the web and can result in lost store sales.  52 percent of on-line shoppers stated that quick page loading is important to their site loyalty.

I posted a couple of blog articles covering things to consider to improve your websites performance take a look here and at this one.

Do you know how fast your website is ?  How well does it perform during busy periods.?  As well as monitoring your key pages every, say, 15 mins. you need to also check your site more comprehensively to ensure there are no "problem" pages within the site.  So something that spiders through your site (in a similar way to the way Google does) that will report your average speed and identify any offending pages would be a useful addition to your armoury..