Hi,
Thanks for your scene. I can see several issues which are causing the performance troubles. Have to say, that during our tests, we haven't found any troubles regarding
Forest Pack and I hope you'll find my following tips useful to optimize your scene to get better render performance.
First, I should mention that
System Units are not set up properly (your scene is out of scale - it's corresponding to
mm, but set to
cm). This leads you to change values for most of adjustments as for example
Global scale of Forest objects, but also to "boost" your lights multiplier values and so on. I recommend you to always double check units setup as later V-Ray is easier to set up.
Probably the biggest problem is the V-Ray's
Subdivisions settings for Lights, Materials and Brute Force as Primary engine for Global Illumination calculation. All of these are set to
220 Subdivisions, which as you can double check for example with this
DMC Calculator causes really HIGH samples values.
Feel free to check
this "V-Ray Render Optimization" article about a possible way how to optimize your V-Ray settings. Also, don't hesitate to ask on Chaos Group's forum as I´m sure they'll help you with it.
As a quick workaround to fix subdivision settings for your materials I can recommend you
this VRayMat Resampler script or any similar.
In case of glass materials I don't think the use of
Dispersion is necessary and also I recommend you to uncheck
Reflect on back side as it's modelled as a solid object. I suppose VRayLight007 should be set to
Invisible.
Hope this helps you a bit and if there will be anything more we can help you with, please let us know. Have a nice day.
Kind regards,