Well I'm no expert in that, so..
BUT the core of LW uses very little CPU for what it is doing. As exemple you can use Acquisition which runs the LW core. What takes a lot of CPU on os x when you think LW is doing nothing is the GUI. I recommend to hide LW when not using it. Notice then how less CPU LW is using. Another way is to change the LW os x theme to a cross platform one. This way you can let LW not hidden and use less CPU.
Bonne chance
Edit: are you sure you are not running as an UP (look under the connection tab...)