Load times for web pages at the news sites -- typically in the five to 7.5 second range -- jumped to a sluggish 12.5 seconds at the height of the Facebook event. Load times at the retail sites more than doubled, to 5.7 seconds from around 2.2 seconds.

Torpid load times were accompanied by performance hits at many websites. At one media site with typical response times in the three to four second range, Compuware showed that the Facebook event caused those times to spike to more than 32 seconds on May 31 and about 15 seconds on June 1.

Similar sluggishness was discovered by Compuware at a major U.S. retail site that typically has response times of two seconds or less. During the Facebook event, those times climbed to 29 seconds on May 31 and to 11.6 and more than 5.8 seconds on June 1.

Those kinds of performance hits can cost a Web enterprise money because they become lost eyeballs. "Our research shows that abandonment and people's tolerance for a slow site increases around eight seconds," Tack said. "After that, people go to a competitor or elsewhere."

He noted that some websites are aware of the potential performance issues that can arise from integrating a third-party widget such as the "like" button on their sites. "If it's not performing well, they'll turn it off so it doesn't impact their site's performance," he explained.