I am on a nMP with 64 GB of memory, running 10.11.6. I haven't upgraded to Sierra as I am waiting for Logitech to fix their mouse driver problem. Twice I have received the "out of application memory" error. Looking at Activity Monitor it shows macrumours taking up almost all of my memory. Once this error occurs just exiting applications does not work. Although memory is released other applications which were running at the time are hung, so I have to reboot. Right now MacRumors is taking ~25 GB of memory in Safari: and as I have written this it has already increased to 27 GB: So I'm going to end this post before my system crashes with the final numbers now being 31 GB.