A few minutes ago, I realized my disk was paging when I ran Vim. Took a quick look at gkrellm, and yes, in fact, I was almost out of swap space, and physical memory was maxed out. The culprit was Firefox, as usual; firefox-bin was responsible for roughly a gigabyte of X pixmap memory.

So I spent some time digging, and realized that I’d had a window open to the Nagios status map for a few hours, which includes a 992 x 1021 pixel PNG. The page refreshes every minute or so. So I closed Firefox, brought up xrestop, opened the status map again, and watched. Sure enough, X pixmap usage for Firefox jumped up by about 2500K per refresh. In the last 10 minutes or so, that number has ballooned to roughly 50MB.