Operating system: Windows 10 Enterprise, 64bit
Graphics card: Nvidia GeForce GTX 970
Broken: 2.80 beta, hash: a1ae04d15a9f, date:2019-01-29 22:41
Worked: 2.79b (official), hash: f4dc9f9d68b, date:2018-03-22 14:10
Short description of error
Texture shading degrades (not smooth) on high dense meshes. Used a wave texture in the example, but the problem is present also using high resolution image textures (I used zebra reflection map). Present in Eevee LookDev and Rendered, and also in Solid mode using high resolution matcap.
Exact steps for others to reproduce the error
Use this file (from the screenshots) and open it with 2.79b and 2.8beta to compare :
In an empty file add a monkey, turn on smooth shading, subdivide it smooth 6-10 times or use Subdivision modifier(6 subdivisions are enough). Add a reflection mapped wave texture and thats it.
In 2.79b the more subdivisions are added the more smooth appears the texture. Used Material display mode so the texture gets visible in the viewport.
In 2.8 beta there is noticeable distortion of the smoothness even with very high subdivision levels.
It's more noticeable with reflection and normal mapping, but present in other mapping modes also.
The problem is not present in Cycles. Only with matcaps and Eevee display modes.