Really? My gaming rig is over 7 years old now. While it was pretty decent for it's time, it's definitely due an upgrade.

But I was still able to run D:E @ 1440p and get a respectable framerate with decent visual quality.

Compared to most other games, I think it's extremely well optimised.

Yeah it runs fine, but not great. I was also put off by this demo (rtx 3080 4K maxed out) https://youtu.be/A7nYy7ZucxM

I think the exact opposite from that demo, they chose Doom Eternal for the first showing of FPS from the 3000 line precisely because it's the best looking title they could get to run at 4k 120+ on the card not in spite of its looks.

Perhaps you just don't like the art style or prefer something that's prettier at low framerates than decent looking at high frame rates? I mean when it came out there were articles literally written about how optimized it is for the quality https://www.tomshardware.com/features/doom_eternal-graphics_.... I'm not saying it's the best optimized game of all time but it certainly is in the top quartile.

Doom Eternal runs better than most of the current Unreal/Unity engine games I've been playing lately, and it looks a touch better too

I haven't tried it on my 4K HTPC (no comfortable keyboard+mouse for FPS on it) but 1440p on a GTX 1080 with all the graphics maxed runs a consistent 60FPS in Vulkan.

Doom 2016 was just way too well optimized so anything after it will seem slow

I felt like the opposite was the case - both Doom 2016 and Eternal ran way better than any other AAA FPS on my machine.

I've read that both represent early push towards truly multithreaded engines, especially on PC, and including graphics part. It's also supposedly why D:E is Vulkan only, as it supposedly goes even deeper with multiple threads sending commands to GPU etc.

Yeah, I also noticed this as well. I think it's more about the level design and lack over optimization passes the levels rather then the engine. Looking in at certain locations would give me massive FPS drops up to 50% reduction.