Viewing the PDF using either the github viewer in Iceweasel 38 or downloading it and viewing it in Atril resulted in 2.1GB memory usage in a spare Jessie / MATE VM I had lying around. Close Atril and Iceweasel, ps -ef to check they're gone, look at top - and Xorg still holds on to 1.14GB.

Kosher it ain't. Proceed at your own risk.