Windows 10, GTX1080Ti
Broken: 2.79 latest master
Worked: probably never
Short description of error
Cycles performance and hardware utilization degrades severely with heavy instancing (I have tried to utilize particle system to generate forest covered mountains). The culprit of the poor utilization seems to be a process described as "Updating Camera Volume" on which most of the time in rendered viewport mode is spent, resulting in usages between 20-30% in both CPU and GPU mode.
It happens only in "rendered" viewport mode, not in the final frame render mode. In final frame render mode, "Updating Camera Volume" is not part of process, hardware utilization seems correct and so does the performance.
Exact steps for others to reproduce the error
1, Open the attached blend file:
2, Switch the viewport mode to rendered
3, Observe poor performance, poor interactivity and low hardware utilization.
4, Switch viewport mode back to shaded and launch final frame rendering (F12 key)
5, Observe proper performance and full hardware utilization
Result: Cycles' performance and hardware utilization reduces drastically with growing amount of instances in rendered viewport mode
Expected; Cycles' performance and hardware utilization is consistently good between viewport and final frame mode regardless of instance count.