Works great when it's working, and I was hoping to roll this into my workstation toolkit - BUT it has a MAJOR bug that makes it completely unusable in practice: when using in conjunction with any fullscreen HTML5 player, this extension will prevent the GPU from correctly leaving (but not from entering) any of its sleep states - effectively crashing the entire system the second it goes to sleep, with the potential to brick the GPU and/or mobo bios any time it happens. Tested in clean installs of Firefox Quantum, Firefox ESR, Waterfox Classic, Waterfox G3 and Waterfox G4, on multiple fresh workstation images (1x W7 + 2xW10) each with different GPUs (GTX 970, RTX 2060, GTX 1080) and substantially different baseline configurations including drivers; 100% reproducibility on every one of them: everything system-wide is ship-shape and working 100%, but add this extension and let the browser idle until it goes to sleep = unresponsive system until hard reset.

Not usable in its current state for this reason.