Think Facebook's your biggest productivity killer in the office? Think again. Social network-obsessed employees just might be your highest performers.

A recent survey by the data analytics firm Evolv suggests that employees who use up to four social media networks are exceptionally productive--and they stay in their jobs longer, too.

Evolv gave its survey to applicants seeking positions at its call center clients, and garnered about 100,000 responses. Of the call center employees, whose positions ranged from sales to customer care, approximately 5,000 did not belong to any social networks at all. Thirty-three thousand belonged to between one and four networks, while only 1,300 belonged to more than five.

This tiny group of social network butterflies, however, ranked as the most efficient. Employees who belonged to more than five social networks had a 1.6 percent higher sales conversion than their counterparts and a 2.8 percent lower average call time.

While the data is interesting, it's next to impossible to determine causation. But Mike Housman, the managing director of Evolv, posits that performance may be linked to the sociability of employees who belong to several online networks. Employees that belong to multiple social networks, he says, are likely to be more technologically savvy--making them more adept at their jobs. They may also be more efficient in job-related social situations.

"[They] get what [they] need, get off the call, and move on," he says, citing sales-oriented employees as an example.

Evolv analyst Michael Han added that individuals who have a higher technical proficiency and are more productive also stay in their jobs longer. But this only holds true up to a point.

Housman explains that there is a "u-shaped relationship" between social networking and employee attrition rates. Employees who do not belong to any social networks leave their jobs more rapidly than those who belong to four or fewer. On the opposite end of the spectrum, employees who belong to five or more social networks also leave their jobs more rapidly than those in the middle group. Employees who belong to four or fewer social networks tend to stay put the longest.

Housman acknowledges that there could be a number of explanations for this, but suggests that overly plugged in employees may have difficulty concentrating on their work. "At a certain point you're almost A.D.D.," he says, "You can't stay focused."