Hi
I tried more or less all builds, and have to say, that IR of builds after 24-02-2017 are less stable on my computer. I get crashes caused by different thing such as moving camera, change of sun's position, change of environment map, change of maps of materials, etc. even in very simple and almost empty scenes. New subsampling is great, but IR of daily build from 24-02-2017 is still much more stable, actually I got with it crashes only in cases of moving camera with rendered Forest Pack's objects (still didn't update it from 5.2.0 to 5.2.2), in all other cases, including merging objects from another files, it works really smooth and stable
Win 10, Max 2014, Dual Intel(R) Xeon(R) CPU E5-2660, 32Gb of RAM