[Shamun]

The effect of this would vary per site. If you have a bunch of things loading, then all the JS files will start taking up HTTP requests and slow the load time due to waiting. It would also reduce the bandwith overhead of requesting more files but that difference wouldn't be noticed by much.

If you want to combine your javascript, you will need to find out which scripts can be combined so they load in the order they're supposed to. This could become more work than worth depending on how much JS is used and how much traffic you get.