Recharged is more demanding, as it says in the description. Especially graphics wise it takes quite a bit more computer power. Also the physics are running at a higher update frequency which makes it more demanding. Apart from lowering the graphics quality, you can also run the simulator at a lower resolution, that helps a lot in getting it to run smoother.
On windows you simply add command line parameters to the executable to set the resolution, as mentioned in the manual. You can do that on a Mac too, however I'm not quite sure how to do it since I don't own a Mac myself. This might be of help:
https://superuser.com/questions/466917/how-to-set-launch-options-for-programs-on...
For example, to run it at low (640x360) resolution in a window you pass the following parameters:
-screen-fullscreen 0 -screen-width 640 -screen-height 360