Abysmal performance on external usb drive

Hi, folks.

  I'm seeing -really- terrible performance with an external usb drive on
my freebsd 5.4 machine. It's a matrox one-touch being attached as the only
device on port 0 of an Intel S845W<mumble> based system. And yes, I do have
ehci compiled in and the most current bios for the board :).

  I'd like to buy a vowel please, and apologies for the spammage.

--------------------------------------------------------------------------------
  Dmesg sez the following:

uhci0: <Intel 82801BA/BAM (ICH2) USB controller USB-A> port 0xef40-0xef5f
irq 1\
9 at device 31.2 on pci0
usb0: <Intel 82801BA/BAM (ICH2) USB controller USB-A> on uhci0
usb0: USB revision 1.0
uhub0: Intel UHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
umass0: Maxtor OneTouch II, rev 2.00/2.03, addr 2
umass0: Get Max Lun not supported (STALLED)
da0: <Maxtor OneTouch II 023d> Fixed Direct Access SCSI-4 device
da0: 1.000MB/s transfers
da0: 194481MB (398297088 512 byte sectors: 255H 63S/T 24792C)

--
  Rough i/o test sez:

dd if=/dev/da0s1c bs=16k count=10000 of=/dev/null   yields:
163840000 bytes transferred in 191.111406 secs (857301 bytes/sec)

--
  And.. oh, the pain:

diskinfo -tv /dev/da0s1c
/dev/da0s1c
        512             # sectorsize
        203921109504    # mediasize in bytes (190G)
        398283417       # mediasize in sectors
        24791           # Cylinders according to firmware.
        255             # Heads according to firmware.
        63              # Sectors according to firmware.

Seek times:
        Full stroke:      250 iter in  13.312930 sec =   53.252 msec
        Half stroke:      250 iter in   4.936923 sec =   19.748 msec
        Quarter stroke:   500 iter in   8.466121 sec =   16.932 msec
        Short forward:    400 iter in   3.550715 sec =    8.877 msec
        Short backward:   400 iter in   3.516539 sec =    8.791 msec
        Seq outer:       2048 iter in  10.288395 sec =    5.024 msec
        Seq inner:       2048 iter in  10.269045 sec =    5.014 msec
Transfer rates:
        outside:       102400 kbytes in  98.968530 sec =     1035 kbytes/sec
        middle:        102400 kbytes in  99.359594 sec =     1031 kbytes/sec
        inside:        102400 kbytes in  98.932885 sec =     1035 kbytes/sec