Gurm Ah, interesting! I didn't experience any problems myself when running Marshmallow and Nougat on my LG G4 at the time, but that was an IPS panel and I seem to be fine with those. I would definately recommend trying 9.0 Pie if and when you're able to get it. The fluidity of the UI and animations seems noticeably smoother which should reduce strain somewhat.
I wish more Android devices adopted panels with 120Hz refresh rates like the Razer Phone. I used that device in my local store and it was the smoothest experience I've ever had on Android. But it was overpriced at the time and nowadays it's outdated. Not to mention the camera sucked. Of course there's now the updated Razer Phone 2 but there's no way I would spend over £700 on a smartphone that doesn't even have 128GB of storage.