Low poly Metaball? Reducing resources of metaballs for effecting particles

Hi All

Any way of improving the resources used by metaballs, Have a few in a project for effecting particles (hands via kinect) but as players join the metaballs start to slow the system down framerate-wise.

Looking at the performance monitor where we have to merge all the metaballs together seems to be taking up most of the frame time.

Any ways of optimising the merge process of many metaballs into a particle node?