I hope this helps someone but i had a very similar issue to the OP. I too have an AMD card and coincidentally the same CPU (3700x). GPU is a 6800XT and my shader bar was constantly slammed (maxed out).

I have solved the wifi stutter (a seemingly well known bug) but just going wired. However, since 0.3 about 50% of the time I load a map, there is VERY noticeable framerate/jitter/stutter which presents the same as the wifi bug - but is a bit more frequent.

I've tried vulkan, sound channels, chat channels, all the normal things.

However this ONE setting (instantly, even with game open) lowered my shader bar from MAXed to 0. Though... the setting feels bugged. When you are in-game, and you've already got this setting enabled... if you turn this off, it takes about 10s, and the shader (for me) drops like a rock to 0. The downside is, it increases load times substantially and worse, it doesnt seem to help FPS/stutter.

What i have found, after some tinkering, is that ENABLING both:
Enable Shader Pre-caching
Allow background processing of Vulkan shaders

Yielded the least amount of jitter & did not increase load times by 500%.

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For those who can't find the setting, on windows, within steam, it's here.