Download speed is the top consideration when designing mobile sites and apps, Matt Poepsel, vice president of performance strategies at Compuware Corp. told attendees at the Internet Retailer Conference & Exhibition 2011 Mobile Commerce Workshop in San Diego last week.

Research has shown that while consumers will accept some constraints when using mobile sites and apps, such as mobile devices’ limited screen size, they’re less willing to tolerate slow loading times. 47% of consumers expect a web page to load in two seconds or less, Poepsel said, citing data from Forrester Research Inc., and consumer expectations of mobile site performance are equally high. 58% of mobile phone users surveyed by Equation Research expect pages to load almost as quickly as, or faster, on their mobile phones than their PCs.

“Consumers are saying, ‘I’ll make certain sacrifices because it’s a mobile platform, but don’t also make me wait’,” Poepsel said.

He offered several recommendations for optimizing mobile site performance, using Amazon’s mobile site as a benchmark. For fast loading, mobile site pages should stay small, he noted, citing the home page of Amazon’s mobile site’s 25 kilobytes of data and average loading time of 2.75 seconds as an example to emulate. By comparison, mobile home pages for two other unnamed retailers he reviewed had, respectively, 48-kilobyte and 148-kilobyte home pages, with average loading times of 5.27 and 5.30 seconds.

Poepsel’s other advice on optimizing mobile site performance included reducing the number of connections required to access content, including content hosted by others such as customer reviews; reducing the number of objects (elements of content on the page that can be manipulated by page users) on a page to reduce the number of user requests to the server to access those features; and using a content delivery network to speed data transfer.

He also encouraged mobile retailers to consider their mobile sites and apps from the viewpoint of the consumer. “Don’t just stop at features and functionality,” he said. “And employ optimization best practices from traditional web sites. It’s even more important with mobile’s networks and device limitations.”