Path Tracer in Movie Render Queue VS HighResShot - Memory Usage

I am using path tracer only and I’ve disabled everything in the game overrides but it doesn’t make a difference. The fact that the render starts then incrementally fills the memory before crashing suggests it isn’t to do with streaming or LODs (of which there is none anyway). I often disable streaming with the console command before I use the HighResShot and it’s fine.