Why fuse-sshfs performance is so poor?

["Kirby Zhou" <kirbyzhou sohu-rd com>]

fuse-sshfs performance is poor? It can only reach 10M/s over the
gigabits-ethernet.
On the both endpoint, ssh and sshd processes take the CPU usage less than
20% with a single core of Inteal-E5520.
It seems the speed should be at least 40M/s.

]# dd if=olddata/diskdata count=100000 bs=64k skip=8000 | md5sum 
316211200 bytes (316 MB) copied, 32.2354 seconds, 9.8 MB/s

]# dd if=olddata/diskdata count=100000 bs=4k skip=8000 | md5sum   
28954624 bytes (29 MB) copied, 3.80448 seconds, 7.6 MB/s

]# dd if=olddata/diskdata count=100000 bs=512k skip=8000 | md5sum  
30408704 bytes (30 MB) copied, 4.33369 seconds, 7.0 MB/s


Regards,
   Kirby Zhou    
   from   SOHU-RD   +86-10-6277-8261