Hi Eliezer,
I would definitely expect the Excel Graph to take more time to process than other graphs. The reason is that unlike the other graphs that are drawn directly in PlanetPress in pure PostScript, this one actually calls Excel via an external vbscript. Then, it has to pass the data to Excel, and have Excel generate the graph, which is then converted to an image, and sent back to PlanetPress, which then includes it in the job as an image. So not only does it has to do all this connectivity, but you also end up with an image, which can slow down processing. (images are often what slows down a job the most)
Unfortunately, this cannot really be avoided when using the Excel graph, as this is the only way we can export a graph from Excel to PlanetPress. If you are making a simple graph and don't need it to be very fancy, I'd suggest looking at the other types of graphs available in PlanetPress, as they will perform a lot better.
Regards,
Raphaël Lalonde Lefebvre