That result pretty much limits the issue to the 3DxSketchUp bundle or rb. You should contact 3Dconnexion and see what they have to say.
I had the same problem. Removed every extensions = problem gone
Put only 3DxWareMac_v10-2-3_r2014 back in plugins. Problem is back.
So confirmation.
Pity cause I really like my SpaceNavigator.
There’s a recent topic about this that may be useful:
SketchUp is steadily ramping up memory after installing the driver for 3Dconnexion’s SpaceNavigator 3D Mouse
I read the same thing that the 3D Connexion mouse software can be the culprit to a memory drain. It was sucking up all of my RAM very quickly for no apparent reason for MONTHS! I finally, just today, updated the driver for the 3D mouse and VIOLA! I can run my largest SketchUp files without running out of ram or slowing down my system! Had SU open all day today! Let us know if this is of any help to you.