Get / Set how fast the Particle System Simulation should run to look "normal".
1.0 = normal speed, 0.5 = half speed, 2.0 = double speed.
This is provided as a way of speeding up / slowing down the simulation to have it look as desired, without having to rescale all of the particle velocities, etc. This allows you to use the exact same particle system class to create two particle systems, and then have one run slower or faster than the other, creating two different effects. If you then wanted to speed up or slow down both effects (i.e. particle systems), you could adjust the SimulationSpeed property on both particle systems without having to worry about adjusting this property at all to get the effects back to normal speed; just reset the SimulationSpeed property you changed back to 1.0.
NOTE: If a negative value is specified, the Internal Simulation Speed is set to zero (pauses the simulation; has the same effect as Enabled = false).
Assembly: DPSF (in DPSF.dll) Version: 126.96.36.199