Reduce objects pre-events and post-events (profiler)

I’m trying to improve the performance of my game and having trouble understanding the profiler. I’m seeing the following:

objects (pre-events) 0.99ms
→ StartWaterFlow 0.18ms
→ DestroyOutside 0.00ms

objects (post-events) 0.45ms
→ StartWaterFlow 0.13ms
→ DestroyOutside 0.01ms

As you can see, the two behaviours listed by the profiler underneath each of the pre-events and post-events sections do not add up to the total amount of time recorded for the section. I’ve done as much as I can in my StartWaterFlow behaviour to reduce the time it takes. How do I reduce the pre-events and post-events times further? What is it doing that is hidden from my view?

Does anyone know the answer to this? I’m guessing that the pre-events and post-events not accounted for by the behaviours underneath are some internal stuff that I have no control over?