Re: CPU usage just having a big file aboard

[Richard Stallman]

    I noticed viewing a 2 MB file, the CPU meter would spring to life
    every few seconds, even though it was in a long ago buried
    buffer. Flyspell was off.  top(1) showed it munched quite a bit.
    Must cause more often garbage collection or something.
    Killing that buffer stopped it.  emacs21 21.3+1-9

How about if you run Emacs under GDB, and next time this occurs,
you could try to stop Emacs during that flurry of activity.
The backtrace will tell us what the activity is for.

You might have to try stopping it several times before you catch
it during the flurry of activity, but that won't be much work.