I create a pool of particles and then reuse them after they 'die' hense the setParticleDefaults() method. This saves you haveing to create and destroy a few hundred particles every update and should remove the need for garbage collection of the dead particles and mem allocation for the new particles.
YMMV so give both a try and see what works best for you. :)
YMMV so give both a try and see what works best for you. :)