Employees who use the Internet for personal reasons might not just be wasting their own time. It’s also likely they’re slowing your Web connection down and making it harder for everyone else to get work done.

A few days ago I wrote about the number of people who’ve been fired for wasting company time online or viewing inappropriate content. But the Wall Street Journal recently reported on another problem employee Web use can cause: bandwidth hogging.

When someone watches a video on YouTube or downloads an mp3 off of a music blog, that means they’re downloading big files, which takes up valuable bandwidth space. At most companies, that space is limited as it is, even when people are just working.

The end result is a more sluggish-than-usual Internet. You’ve probably seen it yourself – all of a sudden it takes a few minutes just to load one page or open a single e-mail. There are a lot of reasons why that can happen, but improper use of the connection could be one of them.

That’s another reason you’ll want to work with your IT department on trying to control what employees are doing. You probably won’t want an absolute “No playing videos or else” kind of policy – some people may actually need to stream content for work-related purposes. But it doesn’t hurt to let them know you’re watching and will discipline as you see fit.

And as another incentive, remind them that staying away from YouTube can help prevent some of those Internet hiccups that no one enjoys.