Has anyone else noticed that the game runs way worse (below 60fps) than it should on high end hardware (RX5700XT, Ryzen5 2600, 16GB RAM DDR4), no matter the settings?

I'm on a Ryzen 2600x, 16GB RAM, 1660TI and the game runs at 60fps on the highest settings at 1080p. I play WOTC though, which did optimize the game significantly. I'm not sure how vanilla XCOM 2 runs.

Sounds like an issue with your PC. I'm running an i7 4770k, 32GB DDR3, RX 5600XT @ 1440p max settings and I get over 60. I do get a few odd dips here and there but its above 60 95% of the time.

Id update your drivers, bios...etc, id also make sure you don't have some crazy super sampling setting enabled in the Radeon software.

Another thing to look at is GPU utilization when you run this game.

Guys you should post some video settings and use a FPS counter to make sure you really get those 60fps, and it does not just look like 60fps. My PC is fine, hardware wise, and Radeon settings are left on their defaults. It's just XCOM2 that refuses to run at 60 fps, even on the lowest settings. And just XCOM2.

I just loaded a mission and took some screenshots. You can see the 60fps counter on the bottom right, taken from GOG Galaxy. I also included a screenshot of the graphics settings. I think it might be something with your hardware configuration that's stopping the 60fps target from being hit.

EDIT: GOG won't allow me to attach the images for some reason, so here is an imgur link of the pictures:
https://imgur.com/a/WMHvMZF

So far no frame drops throughout the 95 hours I've put in. Even during heavy effects like explosions and zooming in and out. Are you playing the base game or WOTC? I play WOTC and I've read that the base XCOM 2 is badly optimized compared to WOTC. They apparently did significant rework for the expansion to make the game run noticeably better, so maybe that could be the cause for the slowdowns you're facing?

If not, based on the four things you listed above, it sounds like a GPU bottleneck that would cause those drops. However your 5700XT should be more than capable of running the game maxed. Have you checked to see if it's a driver issue, some sort of AMD issue, or maybe even a heat issue where dust or something can be causing the card to overheat and throttle itself?

I am running the WOTC expansion.
PC is as clean as possible, no dust concentrations on the hardware.
Considering how many people still have performance issues, it might be a complex of hardware/software related issues, hard to nail, since the game was not optimized form the beginning for diverse configurations.

It's impossible that there is an objective bottleneck. Metro Exodus -60fps (foliage shadows turned off), Witcher 3 -60fps, Middle Earth Series -60fps, Sniper Elite 4 -60fps. And all of those games have open world environments with a huge draw distance. Can't justify a top-down strategy game running this crappy, unless it is using only one CPU core.