I do have to say, the Game should be playable for these types of Low End Computers (if their Software and Drivers are somewhat up to date enough), but you will have to cut down on the Render Distance in a lot of cases to make it work.
The thing I use right now for most regular tasks is good enough to run Minecraft and Factorio and its a 1,1GHz Quadcore with Intel Integrated Graphics and 8GB of RAM. Note, it is NOT good enough for modded Factorio sadly, at least not the Modpack @OvermindDL1 uses when we play.
So your mileage may vary but its supposed to be well playable even with low Specs (and I dont even include Mods in those Specs, I only include the Base-Game relevant Parts in them, Mods might increase the requirements, just like for all Games).
And Minecraft really is Garbage, you should not underestimate just how BAD it is, and STILL is even in newest Versions, yet I still get around 30 FPS. (and I consider everything above 20FPS as well playable)
Also remember I like Pixelated Graphics, similar to how Minecraft has them, so no HD Stuff like Space Engineers that eats your Graphics Card.
So yes it is supposed to be efficient and focus way more on Gameplay than on Graphics (though I guess there will one day be people who make HD Graphics Packs for it or so, like Minecrafts Resource Packs)