Decimator has it's limits

I created a very highpoly prop using replication of already decimated plants in Carrara.
It loads fine in Studio and renders ok but is massive polywise
want to actually get it into iClone but no hope in hell of that!
anyway using decimator on it down to 6% works right up until DONE, Preparing nodes
then it stalls at 100%
2 hours so far,
will kill studio and explore other options instead.
just posting as curious just how high the limit is.