Hello Robert,
RC did not crash the last time during reconstruction? Did changing the reconstruction region helped?
The reconstruction process uses both GPU and CPU, the first part (Depth map calculation) of the reconstruction is GPU heavy. This is affected by CUDA cores count and frequency. You never mentioned your PC specs so it is hard to say if it took long or not. You can check this RC benchmark by Puget systems and compare your times with others:
https://www.pugetsystems.com/labs/articles/RealityCapture-Benchmark-1458/
Jakub