why does atril keep webkit2gtk-4.0 processes with ~100GB virtual memory?

I'm using the Cinnamon desktop environment on Devuan GNU/Linux Beowulf (like Debian Buster but without systemd). I've just brought down all of my browser and other significant apps, but - leaving a couple of open PDF documents. Bringing up htop in a console window, I noticed 2 processes named webkit2gtk-4.0, which - while not actively taking a lot of RAM, did have a virtual memory size of 97G and 82 G respectively. Now, the documents they displayed were pretty simple affairs - static, A4-sized, about 100-200 KB each - text, line art, an image or two. I verified that the processes were related to my PDF viewer, atril in pstree I saw it had started these two processes. My question is: Why would atril even need these processes, and why is their virtual memory so large?