I had no idea it was a stingray game. I thought it was only Fatshark stuck on that POS engine haha.
Things like the grenade glitch are going to be more related to th game logic than the engine, but depending on how the engine handles scripting it could be back to being an engine problem.
Overall I've never thought of Arrowhead as a 'quality' developer - I had a great time with Magicka and HD1, but the jank was part of the charm.
There's no real complexity. Computers are first and foremost electric space heaters, a negligible amount of energy is used to perform computation.
If you would be heating a room with resistive electric heating, a computer drawing the same wattage can do the same job while also, in theory, doing some useful work.
If you are just evaluating heating options, heat pumps use less energy to output the same heat.