Poor performance bind9

Hi,

I've compiled in threads to bind9.3.0 (src from isc not ports) using a dual
procssor machine (2xIntel XEON) with 5.3-STABLE and I encounter serious
performance problems (using queryperf from bind contribs):

++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++
Parse input file: once
Ended due to: reaching end of file

Queries sent: 100000 queries
Queries completed: 100000 queries
Queries lost: 0 queries

Percentage completed: 100.00%
Percentage lost: 0.00%

Started at: Wed Dec 8 12:54:37 2004
Finished at: Wed Dec 8 12:57:58 2004
Ran for: 201.589260 seconds

Queries per second: 496.058173 qps
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++

When I compile bind without threads, the result is realistic and nearly
30x better:

++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++
Parse input file: once
Ended due to: reaching end of file

Queries sent: 100000 queries
Queries completed: 100000 queries
Queries lost: 0 queries

Percentage completed: 100.00%
Percentage lost: 0.00%

Started at: Wed Dec 8 12:50:51 2004
Finished at: Wed Dec 8 12:50:59 2004
Ran for: 7.819249 seconds

Queries per second: 12788.951982 qps
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++

Can anyone explain what's the problem here? Is this a issue of bind9 or of
freebsd? Any suggestions how I can use the two processors of my box
without running two (non multithreading) instances of bind listening on
different IPs?

Regards,

Dirk