> I've often heard this type of symptom, especially on FreeBSD. One
> common cause is that BIND9's cache cleaning (prior to 9.4) relies on
> system's malloc()/free() routines, which could run inefficiently on
> FreeBSD (I'm not really sure if it's still the case for 6.1, but it
> was at least for some 4.X versions); and one common workaround is to
> enable BIND9's internal memory allocator by rebuilding BIND9 with:
>
> % ./configure STD_CDEFINES='-DISC_MEM_USE_INTERNAL_MALLOC=1'
>
> This should be very effectively particularly for the case of cache
> cleaning because it will most likely recycle pre-allocated memory
> fragments without involving any system calls or possible-inefficient
> standard libraries.
>

[snip]

Could this affect the problem I'm having (see message "Bind9 Crazy-high CPU
on Linux")? The symptoms are similar, but not the same.