FreeBSD-6 and em interface speed

[FreeLSD]

  Good day!
 I've obtained the following strang results with the em Ethernet interface
speeds on a 6.1-PRERELEASE:
 Polling on:
  UDP stream to FreeBSD: 327843.84 Kbit/sec,
  TCP stream to FreeBSD: 524550.12 Kbit/sec.
 Polling off:
  UDP stream to FreeBSD: 740409.38 Kbit/sec,
  TCP stream to FreeBSD: 794348.44 Kbit/sec.

 It is funny that TCP speed is greater than UDP. It can be related to the
hardware, not to the OS, because I've seen such behaviour on a linux-2.6.
But on linux-2.4 with the same hardware as for FreeBSD and with the same
source host I've got
 UDP stream to Linux: 927891.44 Kbit/sec,
 TCP stream to Linux: 850202.50 Kbit/sec.
The figures are higher and UDP rate > TCP rate.

 The questions: can anyone explain the relation 'TCP rate > UDP rate'? Why
polling slows down the interface? And can FreeBSD stack can be tuned to
get the Linux performance?

 Kernel config deviations from GENERIC:
options	SCHED_ULE
options	ADAPTIVE_GIANT
device	pf
device	pflog
device	pfsync

 System is running at hz = 1000.

 Thanks!
-- 
rea

I often think it's a pity that Noah and his party didn't miss the boat. 
-Mark Twain