This has happened on multiple projects -- this was only a test project I made. When I create a fluid simulation, bake, and render it, some of the frames render out distorted (and those frames take a much longer time for Blender to render; the others work much quicker).
My question is, why is this happening? And is there a way to fix it?
UPDATE: Seems to be related to the motion blur, exclusively in the Cycles engine. When I turn motion blur off, the distortion - both geometry distortion and shading distortion - appear to be gone. When enabled, they occur.
Running Blender 2.75a x64 on Kubuntu 15.04 x64, KDE Plasma 5.3.2, and rendered with 2x Nvidia GTX 660's via Nvidia CUDA for Linux. Latest proprietary drivers used.