ICE Instance Memory Leak?

[Antonieo]

There're bunch of particles in my scene being instantiated into fish, those 
fish are polymesh objects deforming by skelectons envelops.
Everything works perfect until rendering. The XSI render process continuing 
takes up memory, each frame it takes more 10~20 MB, and finally my computer 
runs out of memory. To fix this I've to restart XSI to free the occupied memory.
Is this a memory leak bug?