https://bugs.freedesktop.org/show_bug.cgi?id=110370
--- Comment #2 from andrew.m.mcmahon@gmail.com --- I don't seem to suffer with poor performance even on an obsolete Phenom II x4 955. But now that you've mentioned when I notice a very slight bit of this shimmering effect on my R9 285, admittedly not to the same degree as you. It's quite noticeable on the first red step at the beginning of the game and seems to shift around with the position of the game camera: https://imgur.com/a/IBmHmhd
Using the GOG v2.1.5 release on:
Debian Testing Linux-drm-fixes-5.1 Mesa 19.1.0-devel (git-53f715fafb) Device: AMD Radeon R9 200 Series (TONGA, DRM 3.30.0, 5.1.0-rc1+, LLVM 8.0.0)
Recorded a trace running the x86 & x86_64 build of the game: https://drive.google.com/drive/folders/10lYHjPXwkxVyUCQM2lJgKES_l2_HNKLg