what is the fastest way to update a SceneGraph?

imagine reading in particle position frames from a coordinate
file and displaying them as balls or connected lines so as to
obtain a continuous trajectory.
the scene itself should be able to allow for rotation and translations
while updating the positions.

currently, i am simply creating a new BranchGroup with the new
positions and using the setChild() method to replace the old BranchGroup.
this works, is however very slow once you need to traverse through a
number of Nodes/TransformGroups/BranchGroups by using the
getChild() method. in addition, the rotation/translation gets jerky even
though everything runs as a separate thread. is there a faster way of doing
this?

thanks in advance
m