Operating system: Windows-10-10.0.17134 64 Bits
Graphics card: GeForce GTX TITAN X/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 419.67
Broken: version: 2.80 (sub 72), branch: blender2.7, commit date: 2019-05-27 19:48, hash: rB89207df7222a
Short description of error
Seems like the playback is much slower when a normal map with Tangent Space is used.
FPS goes down from 60 FPS to below 30 FPS when the "Normal Map" node is plugged into the principled BSDF node.
Same behavior when using the Diffuse BSDF and its Normal input.
Looks like the "Normal Map" node is causing the issue. (Only when set to Tangent Space)
When the Image Node is plugged directly into the normal Input of some BSDF, the framerate stays at 60.