Spacer

When you say spacers, are you using the separator or a blank icon? A blank icon is going to use whatever size you have your icons set at, plus whatever border the program gives it. The separators shoulnd't be taking up too much room on the dock, as long as there isn't a lot of blank border in the actual image. If you can find the separator, open it in a graphics prog and see how big the canvas size is...if the left and right borders have alot of negative space, crop it down.