http://www.freebsd.org/cgi/getmsg.cgi?fetch=736507+739644+/usr/local/w
+ww/db/text/2006/freebsd-stable/20060219.freebsd-stable

> > interrupt                          total       rate
> > irq0: clk                      203894894       1000

a clock rate of 1000 Hz is probably to high for a 486 class cpu.
You should add "options HZ=100" to your kernel config to get back
to the 100 Hz that where default before 6.0

Wolfgang
[download]

One of the recent changes (as of 6.0) to FreeBSD has been a change in the polling frequency, given the huge increase in CPU speed of modern processors. Dunno for sure, but this may affect the signal-propagation as well as interrupt processing.