Why is my stats collector so busy?

On a 8 processor system, my stats collector is always at 100% CPU.
Meanwhile disk I/O is very low. We have many databases, they are
accessed frequently. Sometimes there are big table updates, but in most
of the time only simple queries are ran against the databases, returning
a few records only. From the maximum possible 8.0 system load, the
average load is always above 1.1 and from this, 1.0 is the stats
collector and 0.1 is the remaining of the system. If I restart the
postgresql server, then the stats collector uses 0% CPU for about 10
minutes, then goes up to 100% again. Is there a way to tell why it is
working so much?

I asked this problem some months ago on a different mailing list. I was
asked to provide tracebacks of the stats collector, but due to a bug in
the FreeBSD ppid() function, I'm not able to trace the stats collector.

Thank you,

Laszlo