Its extremely slow to put luminaries in the building. This seems to happen after putting ceilings in the floors. Every operation takes 7-12 seconds, and with a building with 300+ rooms its not possible to work efficient. After monitoring the system resources, it does not seem to be a problem with CPU/RAM/GPU, since they only seem to be at low levels always. CPU is never over 10%, memory is at 25%, and GPU is always below 5%.