Fastest browser to run over a forwarded X11 session

Even if you use a browser that is light-weight on CPU and RAM on the server, in this case the limiting factor will undeniably [1] be the network. What you want to avoid is mostly unnecessary screen rendering.

• Turn off "smooth scrolling" and such features. Use PgUp/PgDn instead of continuously scrolling if you have the choice (a single screen update is much faster than 30 just to see a full page).
• Keep a small browsing window (but not so small so you have to scroll a lot more as per previous point).
• Block animated material (animated GIFs are not that common nowadays, so blocking flash will probably do fine).
• Consider using VNC, which will compress the image transfer in a clever way. This gives me a much snappier experience when forced to use GUI over slow connections.
• Don't underestimate text-based browsers if there is something you quickly need to do on the server.
• Proxy and/or port tunneling through SSH avoid/s the problem completely. You just want to transfer the information, it is unnecessary to transfer the complete presentation layer.

[1]: Unless you have a very fast connection (~100Mbps in my experience); then any browser will probably do without being more annoying than using the browser locally. I am blessed with this in my remote needs.

The main reason X11forwarding is showing lag is because of the cipher that you are using to connect with, and not the actual browser itself.

You will find much better performance if you change the encryption to arcfour or blowfish.

I had the same issue, and found that this pretty much eliminated all of the lag. The downside is that these ciphers are not as secure as AES which is the typical default.

If you are on a windows machine using putty, you can change the encryption cipher selection policy under Connection/SSH/ . You should also enable compression on that same screen and save it as the default for the connection you are loading.

If you are connecting from one linux machine to the other, the connect string looks like this: ssh -XC4c arcfour,blowfish-cbc hostnameorip

There are a few browsers that run a bit (to much) better over X11 forwarding.

Midori is a lightweight, tabbed browser that should run well.

Xlinks2 should work over X11 forwarding pretty well as well.

uzbl and surf are both browsers I've used that should work well over X11 because they're very minimal.