The most reliable way to reproduce this for me has been to open and close a lot of windows. If I have a set of Orion windows that just stay open, kernel memory doesn't seem to change much. But if I open and close windows frequently, kernel memory increases quickly.
This recording was made in the Guest user with a clean profile. Notice how kernel memory increases each time I close a window. Multiply that by a few days or weeks, and it will increase to gigabytes. I also opened pages with lots of large images and videos (like Apple product pages and Flickr) and scrolled through them. Not sure if that's necessary, but I didn't seem to be able to reproduce the issue quite as readily with blank windows.
When I do the same thing with Safari, kernel memory does increase, but not by as much (the most I saw was 5 MB), and it goes back down within about 30 seconds of closing a Safari window.