In settings.cfg, at the bottom, I've always made a custom terrain settings with Medium/High terrain detail but Low ocean detail. It makes the game run much, much better on my laptop.
As of 1.3, I see a small bug. Adding my custom setting doesn't work like it used to. I can add my custom terrain preset, so it seems, but the name doesn't come up. It instead repeats High (i.e. there are two settings called High). When I select the second High setting (presumably my custom setting), click Accept, then return to the graphics settings, it says "New Text". When I try the game, however, I can see that my custom setting has been correctly selected.
Also, when I try to change the Low, Default, or High preset names themselves in settings.cfg, the name change does not show up in the setting menu in game.
Can anyone reproduce this? If they can I'll submit it to the bug tracker.