All managers know employees often stray from their work to do some online slacking. But is there a bigger impact, even beyond all the lost productivity?

Researchers at tech firm Palo Alto Networks recently conducted an in depth study of 60 companies to determine how their Internet bandwidth is being used.

The results: A big chunk of the pipeline is being hogged by timewasters.

Online video is the video is the biggest culprit. At the companies studied, 10% of all the bandwidth was used for YouTube and Slingbox (a service that lets you watch TV shows on your computer) alone.

As far as productivity goes, many companies leave it up to managers to make sure employees are getting their work done. But when workers do things that hog bandwidth, things get more complicated because it can cause the Web to run slowly and zap everyone else’s productivity.

HR needs to work with IT to come up with a policy that works for the company and its resources — for example, it may be a good idea for most companies to ban online videos, streaming music and other hefty downloads.

Tags: bandwidth, Palo Alto Networks, wasting time online, YouTube