Just a though, but as bandwidth costs money, any way of reducing the amount of data through your server should save money on forum running costs.
I know you have the option to upload photos and host them on the PL server. This is obviously where most of the band width goes. If all photos were hosted externally (Photobucket etc) and the link embedded it should cut down on the server capacity and hopefully save some running costs.
To the reader, there is no difference, as the photo is still there and it would also remove that annoying delay when you click on an embedded thumbnail while you wait for the picture to load.
Just a thought, but another forum I use (6K members) does this and halved their monthly costs.