Low perf of i386 6.0 on dell poweredge 1850 bi-Xeon 2.8ghzDualCore

[Eric]

Still me ;=)

I do new test and have this information to add :

Freebsd 6.0 with bi-xeon dual core and smp kernel is two time more slower 
than Freebsd 4.11 with simple bi-xeon
If I configure freebsd 6.0 kernel without smp it's 1.5 faster than with.

Here is a resume :

The test is simple mysql multi-query php script.

With freebsd 4.11 on bi-xeon it took                                     31 
sec
With freebsd 6.0 on bi-xeon dual core without smp it took     48 sec
With freebsd 6.0 on bi-xeon dual core smp it took                 62 sec.

Any idea of what's go wrong or way to have expected result?

Thanks,

Eric.