High CPU load after pressing arbitrary key (mostly in C mode)

[Michal Sojka]

Hi all,

I experience a weird a problem. It appears more or less randomly,
typically after using emacs for several hours. The responsiveness of emacs
starts to be very slow. Whenever I press a key, for example to type some
character, it appears on the screen in let say half a second. By
pressing several keys fast, the CPU load goes to 100%.

This happens mostly in C mode. By switching to another mode, the
response is better but occasionally there is a long delay even in the
other modes.

I workaround this by exiting emacs and starting it again. Is there any
way how to debug such problems. For example tracing all functions that
are called when a key is pressed?

I tried to switch off font-lock-mode, but it didn't change anything.

My emacs is:
GNU Emacs 23.3.1 (x86_64-pc-linux-gnu, GTK+ Version 2.24.4), Debian.

Thanks,
Michal