Version 3.9.6 of the RSU-Client is now released and available in the LaunchPad PPA and from dropbox.
This new version contains Nvidia Optimus support through the use of bumblebee and primusrun.

As a last note, the LaunchPad PPA packages are now automatically built from the git repository, this means that the packages are updated automatically and should be available within 1 day after a release.
Thanks to the RuneScape player Tzbob for telling me that primusrun lets RuneScape use the Nvidia GPU on Nvidia Optimus Linux PCs with working OpenGL.
After he mentioned this to me I started working with the module which will make the runescape script automatically use "primusrun" if it is available on the system (if you told the script to use primusrun).

A full release is planned on Monday the 17th December, if you want to try it out beforehand you can find the beta here:

Tests done by Tzbob shows that the Nvidia Optimus card gives better performance in runescape on Linux than on Windows!

If you need more info about primusrun then please read this article on
The beta of the RSU-Client is now available at GitHub!
Please test it and give feedback about the addons functionality in the Community - Linux thread on the RuneScape Forums.