At 01:11 PM 12/11/2006 -0500, you wrote:
I've added a SVG driver to PLplot ( 
SVG (Scalable Vector Graphics)

Well done ! This was something that I was always going to do eventually, but sadly never got around to… so happy to hear you did.

The generated files are similar in size to their postscript equivalents.

I've only had a superficial look at it, and don't have the time for a couple of days to look properly, but it seems like you are saving as an uncompressed SVG stream. If you are compressing them, then ignore what I am about to say… As the libz library is usually present for the png driver, if you were not using compressed SVG files, it should be quite trivial to support to a libz compressed SVG stream. They compress very well indeed.