Ok, so I’ve looked at that page and the RAM listed there is reasonably good, and both of the storage drives (which are SSDs) are really good, so memory reading and writing speed are not the issue here.
The computer comes with a “gaming centre” application built-in, you should check the settings on that and what settings it uses when you’re playing Stonehearth – you can use it to set up the way that programs run in the background so you’re not wasting processing power on other things, and probably also do some basic memory management too. I wouldn’t be surprised to find that by default it tries to spread the work out over multiple cores (which the game doesn’t support), so setting up this program to assist with “maximising” a single core instead would probably have a big difference for Stonehearth and some other games which need a lot of processing but only run in a single thread.
Your computer has plenty of power, but I don’t think that most of it is getting used by the game. Hopefully that built-in control centre lets you fix part of that situation by a) turning off/pausing background things (like animated desktop wallpapers, fancy Windows UI effects, other programs and background jobs) when you’re playing the game, and b) explaining to the computer how best to use the available processing power.