Running SSH X forwarded session from my Ubuntu 12LTS client to a SLES server results in very slow(seconds per mouse click) GUI app(on the server) performance.
Using a windows client from the same LAN with Putty and XMing to SSH to the same server hosted application is blazing fast(instantaneous).
Likewise, SSH -X from other SLES machines to the same server hosted application is very fast.
I have tried numerous combinations of ssh parameters(listed below) with no effect on performance. The Ubuntu client is painfully slow while PuTTY/XMing are very fast.
-X -C -o GSSAPIAuthentication no -c blowfish-cbc UseDNS no -- on the servers sshd_config