Community
Can you make create screenshot, you render setting, how many samples in light, arnold subdivision interaction, and your pc configuration?
Also try to render with "Ignore Texture" first, "Ignore Subdivision and Displacement" second, and "Ignore Depth of Field".
https://support.solidangle.com/display/A5AFMUG/Feature+Overrides
Its good to go with decent sample setting and make tx files,that has huge render time difference for substance textures.