chexmix

Hi -- Boy do I love this game. However, my most up to date machine is struggling to run it. Motions are jerky, sometimes I have to repeat actions because they fail to 'take', and my laptop vent is burning my leg. Note, I am running KSP via Steam on a Linux box (Slackware Linux, for what it is worth). This laptop is ca. 2012 -- a bit old, sure, but has a core i5-3210M CPU @ 2.50GHz and 16gb of ram. Should this not be adequate to run the game well? What else should I be considering? I just installed the Making History expansion. Could that be causing problems (I didn't think this was a 'mod' so posted here)? I'm looking into changing settings, too, but any insight would be welcome. Thanks, Glenn