Ok, this is not explaining why firefox is so slow but how you can do very similar stuff with other tools. Ok the reason for me to do "ssh -X" for firefox was, to use a special IP then, hence I opened firefox from that machine with that special IP via "ssh -X". I found this solution to my problem here:
tsocks is a very powerfull program:
aptitude install tsocks
vim /etc/tsocks.conf
server = 127.0.0.1
server_port = 3333
server_type = 5
ssh -ND 3333 remotebox &
tsocks firefox &
tsocks thunderbird &
Though Goolge Chrome will not work with that and maybe many other tools too, it saves me very much time and trouble. And if you concerned about the browsing environment since you are now using a local firefox just using the network traffic from a diffrent host, I strongly recommend you use the sync feature in new firefox which is also able to sync addons since firefox 11.
I am happy now :D.
1just to clarify, firefox is noticeably slower than chrome or epiphany when you run all three over ssh X forwarding?
i don't have a good explanation for that specifically, but you might try NX instead, or VNC if that doesn't work. the X network protocol was invented a long time ago, and it shows its age. NX in particularly is often much better for remote desktop work like this on *nix. – ryan – 2011-12-29T16:42:47.397
Yes, you understood my question very well. VNC and all NX stuff has some drawbacks: My workstation has a very big resolution 2500x1600 but my notebook, not. At last I tested the VNC stuff I always has to reset my resolution. Another fact which disturbes me: I often see compression artifacts. If X11 forwarding would be as fast as with Chrome or Epiphany I would be perfectly satisfied! – math – 2011-12-29T16:52:46.080