How to improve transfert rate with rsync

[guy cadoche]

Hello,
1) I am using rsync with gentoo and all emerge are very fast 400 kb/s 
ADSL connections.
When I am using rsync with two computers with the same bandwith 
connection (ADSL 400 kb/s) transfert is very low (40 kb/s).
options are "rsync -avzub".
How can I improve the rate of transfert ?
I saw That it use sftp. Is there a configuration file for sftp that 
improve the transfert ?
2) How can I see the transfert rate of the file (like with scp)
Thank you
guy