How many meteors to launch each frame (1 to total pixels on your tree. Numbers ike 6-12 are reasonable.):
Each frame, this many meteors will be randomly launched on your tree
This directly increases the time of the effect generation. I use values 6-12 , and i fit.
Also if your target tree has more pixels, it will take more time.
I might suggest everyone have one target that is smaller, say 32x40 BOT/TOP and use that for trying effects. When you get what u like , just select your larger target and apply your effect to it.