Using 2.82a. I’m rendering a scene and motion blur is slow. Just wondering if that’s just the nature of it or if there are common mistakes people make using it.
Motion-blur rendering (in that old version!) would render and each time re- render several frames surrounding the target, then blur them together. When rendering several frames in succession, it never seemed to be able to cache them.
In my experience, other, simpler forms of “blur” are equally effective. Modern versions of Blender also give you considerably more options.
I’ve found that in my case it was because of microdisplacement. Once I turned that off it rendered normally.