Many large corporations launching sites on a similar scale have had certain advantages, says Mr. Probstein. “They can beta test, start small, reengineer, and work up to the massive size of HealthCare.gov,” he adds.

Inefficiency is one of the site’s biggest challenges, says Michael Smith, engineering vice president at Compuware APM, which has conducted a technical analysis of the HealthCare.gov site. This is predictable given the diversity of information sources – from individual states to the IRS to dozens of private insurers – and the fact that the site must work with nearly 50 different subcontractors to pull together its web of data, he says.

The site includes multiple versions of overlapping monitoring software, Mr. Smith notes. These programs track users’ keystrokes and help the site deliver faster service based on the way clients actually use it. But HealthCare.gov has no fewer than five such programs, including Google Analytics, Chartbeat, and Pingdom, and they all do similar monitoring and feedback.

That suggests that each contractor built its own monitoring service into its calculations, he says. On one hand, that’s “a good thing, because the monitoring helps them improve services.” But, he adds, “the overall site could easily reduce that to one service.”