I'd like to request an AFK mode for the game on PC, so I can keep the game running in the background without it hogging so much of my (admittedly lower end) PC's resources.

I have to only run it when I'm not doing anything more than reading, as even youtube videos stutter and freeze if it's in the background.

The idea behind the AFK mode, is the game still runs and progresses through waves, but it doesn't do all the animations, calculations, and whatever it is that causes it to use so much of the CPU.