Low perfomance when read from usb flash drive

[Artyom Mirgorodsky]

> FreeBSD-8-Current
> 
> dd if=/dev/da0 of=/dev/null bs=64k count=10000
> 10000+0 records in
> 10000+0 records out
> 655360000 bytes transferred in 60.320972 secs (10864546 bytes/sec)
> 

Fantastic!!! Today result:

dd if=/dev/da0 of=/dev/null bs=64k count=10000
10000+0 records in
10000+0 records out
655360000 bytes transferred in 27.736688 secs (23627911 bytes/sec)

Many thanks.