Website Performance of US Web Shops

Introduction

 

A press release including observations, analyses and website performance statistics of the top 100 US web shops that were monitored by WatchMouse can be viewed at: WatchMouse Press room

 

Availability

The uptime of each of the 100 sites is presented below. In accordance with industry standards, availability of ≥99.9% is regarded as 'good' while anything below 99% is regarded as 'poor' site uptime. (99% uptime equals over 80 hours downtime per year, or about 1 business day per month).

 

 

Performance

The performance (page load speed) was measured for the top 100 web shops of United States and the results are displayed in the graphs below.

 

 

Site Performance Index

Combining a site's availability with measurement of speed and load time, Nimsoft Cloud Monitor gives each monitored site a Site Performance Index (SPI). The SPI represents the relative website performance. An SPI below 1000 indicates a site that performs 'well' and has a good user experience. An SPI between 1000 and 2000 represents an 'acceptable' user experience while an SPI of more than 2000 represents a site with serious user experience issues.

 

Methodology

WatchMouse monitored the availability (uptime) and performance (page load speed) of the top 100 online shops in the US from October 28 through November 27, 2010.

 

Availability

One of the Nimsoft Cloud Monitor monitoring stations retrieved the homepage of the site every 5 minutes, without graphics, frames, etc; and redirects were followed. Each HTML page was expected to download within 8 seconds, without any errors. If that time was exceeded, it was verified by one of the other Nimsoft Cloud Monitor monitoring stations. If this station also established an error, it was counted and recorded as 'poor availability' or 'unavailable'. Server errors (i.e. 500 Server Error) are not verified by a second monitoring station, and those errors also contribute to the uptime percentage.
An uptime of 99.99% or higher is extremely desirable for high-profile companies and companies that achieve high turnovers through their sites. Many companies stipulate an uptime of 99.9% as a minimum requirement in the Service Level Agreement with their IT department or provider. An uptime below 99% is usually regarded as unacceptable. In the uptime table above these limits are indicated with colors.

 

Performance

For each HTML page retrieval all timing stages were measured and averaged over the survey period for each website. Errors are not included in the performance chart. Please see below for the definitions of the individual timing stages:

• Resolve time: Time (in ms) for resolving the IP address of a host name.
• Connect time: Time (in msec) for connection phase of TCP/IP.
• Processing time: Time (in msec) from first byte sent to first byte received (also known as 'time to first byte').
• Download time: Time (in msec) from first byte sent to last byte received (also known as 'time to last byte').
• Total time: Total time, i.e. connect time plus download time (in msec).

 

Site Performance Index

The Nimsoft Cloud Monitor Site Performance Index (SPI) quantifies the user perception of speed and availability of a site in a single number. The SPI is computed by adding up the time needed to load the main page, adding a penalty for each failed request. The higher the number, the lower the customer experience of the site. Sites with an SPI of 1000 perform well, whereas an index of 2000 or higher is an indication of a seriously negative user experience.

The Nimsoft Cloud Monitor Site Performance Index was developed by Dr Peter van Eijk and his team, based on many years of practical experience and research into the performance and availability of computer systems. The current version of the SPI is computed as follows.
One of the 42 test stations of the Nimsoft Cloud Monitor worldwide network retrieves the homepage of the site at a fixed frequency, without images, frames, etc. This HTML page is expected to download within 8 seconds, without any errors. If this time is exceeded, or if an error occurs, this is verified by one of the other test stations. This check is called the "2nd opinion check". If this check also reports an error, this is counted as "not available".
All 2nd opinion checks, and all successful checks, are taken into account. All the connect and download times of all successful checks are added together. For each failed (2nd opinion) check, a 10 second penalty is added. The SPI is the sum of these, expressed as an average over 1000 checks.

This website performance monitoring research covers the websites of the following organisations: Amazon.com, Apple, Balenciaga, Bestbuy, Bloomingdales, Blue Nile, Borders, Calvin Klein, Circuit City, Dior, eBay, Half.com, Hugo Boss, IKEA, J Crew, Karmaloop, Kohl's, Lands' End, Macy's, Neiman Marcus, Overstock, QVC, Saks Fifth Avenue, Sony, Victoria's Secret, WalMart, Zappos, American Apparel, Barnes & Noble, Bergdorf Goodman, Brookstone, Dell, Gucci, Hermes, New Egg, PRADA, Ralph Lauren, Samsonite, Sharper Image, Staples, Versace, Shopping.com, Costco, Eddie Bauer, Kate Spade, HP, Virgin Records, Buy.com, Dick's Sporting Goods, Kenneth Cole, NineWest, Tumi, Net-a-Porter, Anthropologie, Sears, Target, Barney's, Dillards, Juicy Couture, Restoration Hardware, Radio Shack, Sports Authority, Coach, Nike, Nordstrom, Crutchfield, Steve Madden, CDW, BCBG, GameStop, Levi's, KMart, Toys R Us, Bed,Bath & Beyond, RedEnvelope, Dolce and Gabbana, Hammacher Schlemmer, VistaPrint, Office Depot, Bluefly, Office Max, Gap, ShopBop, Home Depot, Laura Ashley, Abe Books, Banana Republic, Z Gallerie, West Elm, Abercrombie and Fitch, Bulgari, Pottery Barn, Williams-Sonoma, Guess, JC Penney, Louis Vuitton, Fry's Electronics, Footlocker, Gilt Groupe, American Eagle Outfitters.

Learn more about Nimsoft Cloud Monitor at www.watchmouse.com