sorry, it seems this thread was overlooked. So far, no other useres have reported any memory related issues, so I don't think it is actually a bug in PDFCreator, or it is something which is only noticible under certain conditions. Some of our power users print ~50000 documents a day with PDFCreator, unless you have an ever larger throughput, I doubt it is the volume. Do you have any actions configured?
Have you already tested 2.5.3?
We will check if this is reproducible here in the meanwhile.