How can I use 8 curves having Force and Curve in physics panel? Notice that Curve Guide is 4 time slower than Force and Curve.
For slower particle speed change the lifetime value of the particle system to a larger value.
For faster particle speed change the lifetime value of the particle system to a smaller value.
- The setting is in the particles settings emissions panel
- So the length of a curve and the lifetime combine to create speed
- The arrow in the Blender screen capture below shows the setting with an arrow
A previous answer regarding multiple Curve Guides ..
I am addressing two different topics since I cannot tell how many different concept questions are in the Blender question above.