Let me start by saying I know all the factors that cause slow rendering.
This question has to do with the color depth with the new Hitfilm Pro.
In the past ver 3, 4 and 2017 changing the color depth to 16 or even 32 would only increase render times by about 10%. Now I have noticed that if I try and render anything above 8-bit the render times seem to increase massively. 9.21 sec clip (no motion blur) 5 minutes at 8bit to 6.54 hours at 16bit as example.
I'm working only with 3D models (no video footage) and a background. Model texture maps are 24bit 4k and the background image is 24bit 2k.
I would love to share the project file BUT I can't due to the fact contains a Jetstrike model and textures.
Aside: I sent the project file to support and they (Axel) have returned a verdict of motion blur causing crashes during compositing which I knew had caused problems in the past. I'm sure I've left it off when working and turn it on when rendering though. But I'll keep note of it in the future.
This is a side note pertaining to 16 bit and crashes while working with split views. I have another project that contains Krammer's Star Wars pac (corridor and R2D2) that I built to test the new spherical or planer reflections that crashes if I try and split the views while in 16 bit or higher. I get the same issue when working with the Jetstrike models.
So...question. Is anyone else experiencing any issue like I have described above?
EDIT: Levels, curves, blur, letterbox are the additional effects. All of them are disabled. No effect on render time at 16 bit +. All paths point to motion blur being the culprit in the case of the Jetstrike render