Glad the refresh rate change brought The Shining close to normal: at 24 Hz the card packs 24 frames a second instead of 60.
Avatar: The Way of Water is about as heavy as it gets. Which GT 1030 you have matters a lot here: the GDDR5 version has around 48 GB/s of memory bandwidth, the DDR4 one around 17 GB/s, and this work moves a lot of memory per frame. A GDDR5 card should keep up at least as well as an Intel N100 mini PC, which Hades runs on, so if yours is GDDR5 and still struggles, that is something for me to fix, not your hardware.
Your report already points at two things I want to improve for cards like yours: presenting a frame ahead hurt instead of helping on a GTX 10 card with driver 580, and each decoded picture takes an extra copy on NVIDIA before it is drawn. The diagnostic will show which card you have and where each frame's time goes, so it really helps; I'll use it to make the next version lighter on this kind of card.