Re: sit-for

[Richard Stallman]

    Update: it still happens.  I am working for a while in a web browser,
    suddenly the fans engage, the Emacs frame (not even mapped when this
    happens) shows a very slow and erratically blinking cursor, and `top'
    shows that Emacs is consuming close to 100% of CPU power.

Please run Emacs under GDB, so you can suspend it several times while
this is happening.  Make a backtrace (C and Lisp) each time, and by
and by you'll see a pattern which shows what part of Emacs is doing
this.