RooFit: Memory usage when generating with Conditional PDFs

Dear all,
I’m trying to use RooFit to make a complex study that involves generating several hundred thousands of events with a PDF that is the sum of several conditional PDFs.
I’ve seen that going from simple PDF products to Conditional ones (that I need to use) increase the use of Physical Memory by a factor greater than 10 (or maybe more). Is this expected? In this case, when I try to generate the full statistics I need I end up with big memory problems (the job eats more than 3Gb memory and then crashes).

Is there anything I can do to improve the Memory performance [apart from splitting the sample in smaller subsamples]? (I already use RooHistPdf in my conditional product in order to keep it simple without parameters…)