I left some forum pages open for several days. Most of them I left open as background tabs without touching them. Today, when I looked at the memory usage of those tabs, it was hundreds of megabytes per page, with the heaviest pages taking over 2 gigabytes. Closing any of those tabs and opening the same URL again results in normal memory usage (<100MB in this case).

This is a Windows 10 PC with Google Chrome displaying the pages. I didn't have any similar leaking problems with other sites I leave open, and I have quite a few of them.