As I found before outbreak and have tested twice now afterwards as colonies go above the 2000 cycle count and higher time stretches longer and longer each day. Currently my latest test colony is at cycle 3033 running on x3 speed. Assuming normal conditions, a cycle at x3 speed should take 200 seconds to complete. Timing it showed the cycle took 403 seconds. Another test I ran month or two ago had a friend's colony lasting until cycle 7060 before inevitably dying from the same issue; cycle times increased to the point that her dupes died in their sleep from starvation because the night cycle lasted too long. I'm attaching both her save and my current colony.
Run a colony for more than 2000 cycles.