It looks that all is set rhight. It uses GPU but only when background is not transparent. Other case it uses CPU.
Rhino 6 SR14 2019-5-7 (Rhino 6, 6.14.19127.17141, Git hash:master @ 5b633aaa430941b76f5789a0ce3bb670ce06947a)
License type: Commercial, build 2019-05-07
License details: LAN Zoo Network Node
Windows 10.0 SR0.0 or greater (Physical RAM: 32Gb)
Machine name: SWAC
Non-hybrid graphics.
Primary display and OpenGL: NVIDIA GeForce GTX 1060 6GB (NVidia) Memory: 6GB, Driver date: 3-1-2019 (M-D-Y). OpenGL Ver: 4.6.0 NVIDIA 419.35
OpenGL Settings
Safe mode: Off
Use accelerated hardware modes: On
Redraw scene when viewports are exposed: On
Anti-alias mode: 4x
Mip Map Filtering: Linear
Anisotropic Filtering Mode: Height
Vendor Name: NVIDIA Corporation
Render version: 4.6
Shading Language: 4.60 NVIDIA
Driver Date: 3-1-2019
Driver Version: 25.21.14.1935
Maximum Texture size: 32768 x 32768
Z-Buffer depth: 24 bits
Maximum Viewport size: 32768 x 32768
Total Video Memory: 6 GB