Do Compression and CompressionLevel apply to Dynamic port forwardings (socks5) ?

Hello,

Version: OpenSSH_5.3p1 Debian-3ubuntu6, OpenSSL 0.9.8k 25 Mar 2009

I would like to use socks5 with compression on a slow WAN line.
I use this command : ssh -p 51001 -C -o "CompressionLevel 9" -g -D <ip-of-this-machine>:51001 root@<remote-machine>

Generally this works but I notice there is no difference in speed 
if I use CompressionLevel 1 compared tho CompressionLevel 9.

Does compression work with Dynamic port forwarding at all ?

Thanks, muellejo