Do you have experience with consoles?
I'm curious about the performance of Unity on the Switch's Tegra T210 vs Playstation 4's AMD APU. I have seen a few games performing far better on Switch, like Broforce: It peforms fairly well on Switch while it has long loading times and it struggles like hell in the last levels on Playstation 4 Pro + Boost Mode.
It could be a resolution thing, i havent measured them.
I do, specifically in the context of VR for current day stuff for Unreal and Unity, and non-Unity engines for older (Vicious Engine, Renderware and a bunch of custom environments).
I can only speculate on the issue you're describing, as I'm on the creative and production side of things, so I know a little about it on the bird's eye view level as it impacts design, performance optimization, testing and planning, but not the hardware side. More technical folks may be able to describe the below better.
Sometimes it's not specifically the hardware, but issues where a version of X Engine - say Unity - won't play well with the platform-holder SDK. Sometimes one is ahead or behind the other in terms of bridging the ability to turn features on and off, or fix bugs allowing that to be as-designed.
For example, a former team I advised built the Ghostbusters VR games, and a key tech issue was that the team couldn't spatialize the audio in VR because the audio driver in Unity would cause a major crash bug when deployed through PlayStation's SDK. So we had to scrap spatialized audio... until we eventually just delayed the release to focus on something else, and the issue was fixed for when the team could come back to finish it.
Other variants of an engine-to-platform SDK bug included a "hall of mirrors" re-projection bug which despite being psychedelic/trippy, would induce nausea that would happen between a version of Unreal 4 and PSVR. Unfortunately it was the latest version of the engine at the time, and it was needed to ship to PSVR, so we were stuck. Meanwhile, this issue affected anything needing re-projection, like our 'Spider-suit briefcase' and the 3D environment loadscreen we wanted.
This was because of the same issue described above - the SDK and the deployment environment had some issue between them where features wouldn't work in the context of engine + SDK.
So for Spider-Man Homecoming VR, we had flat 2D loading screens, instead of the small target play area we wanted where people could mess around while the game loaded.
For BroForce (one of my favorite co-op games I unironically played-through with my younger brother), I'd guess it's something to do with memory management at real-time or too many shaders with transparencies on them. I'm not sure if Unity is still 'faking' 2D (running 2D objects in a framework that is running in a 3D engine), but sprite/texture sheets, unless managed very carefully, eat up draw calls and that tends to affect performance on games that don't look like they should have those issues. And yeah, could be a resolution thing; i.e, it wasn't optimized for it, but just running through the upscaler thing.