Popcorn fx 1.12 Speed of particle in Path Sampler

i tried to learn Popcorn fx for iclone it must be 1.12 version.
I use Path sample- to make circle of riding particle

But i cant understand- how change speed of this particle effect!

Here a link to video of my progress

if i use
float st=spawner.LifeRatio;
Position = Path_1.samplePosition(st);
I have- 1xSpeed
Position = Path_1.samplePosition(wavesaw(3st));
or
Position = Path_1.samplePosition(frac(3
st));
i have 3x speed
but i cant understand -how do -for example- 0.5 of speed?