At extremely low speeds or time scales (approx. < 0.25), particle systems will appear to stutter. This is due to a bug in Unity's particle simulation method.Bug report reference
Stutter on low time scales
Forced local simulation space
Because Chronos has to use manual resimulation of particle systems to enable rewinding, the simulation space is always updated and therefore local. There seems to be no workaround at the moment.
No particle collision detection
Likewise, when manually simulating particles, collision events never get triggered. It is unsure whether this is intended behaviour or a bug for Unity, but there seems to be no workaround at the moment.