Online shoppers have little patience for web sites that take too long to load or that malfunction when processing transactions during peak times such as holidays, suggests survey data by Gomez, the web-performance division of Compuware Corp.

Web site errors can drive nearly one in five online shoppers to competitors’ sites, the findings suggest.

The findings are based on surveys conducted between Dec. 16 and Dec. 22 of 1,500 consumers who had bought products or services online over the past nine months. Equation Research conducted the surveys, which focused on peak shopping times such as Christmas and Valentine’s Day, on behalf of Gomez.

A third of respondents reported a bad experience on retail and travel web sites during the 2009 holiday season, Gomez says. 41% of respondents said they would tolerate no more than two such experiences before abandoning a retailer’s web site. Consumers were not all that tolerant, says Jeff Loeb, Gomez vice president of product marketing.

78% of survey respondents have gone to competing web sites because of poor performance, Loeb says. Of those, 47% report leaving a web site with a negative view of the retailer’s brand, he says. Additionally, 42% report spreading those negative perceptions via blogs, social networking, e-mails and word of mouth.

The stakes are high for online retailers, as 51% of survey respondents say they spend a significant portion of their online purchasing dollars during peak times such as holidays. Gomez estimates that Internet shoppers spend an average of $1,050 annually shopping online.

The first lesson for online retailers is that performance matters on peak time, Loeb says. Secondly, in terms of what they can do, [online retailers] need to be much more proactive in determining if their web application infrastructure can support [peak time] shopping.