@ gmvgmvgmv - I have found that using one of the many free memory optimizers available often helps.  If nothing else, you can watch the memory slowly being released/recovered.  I too, have been using Bryce for many years, and found that Bryce takes some time for memory to "settle" after loading and after complex rendering.  A very large/complex scene may take 5 minutes or more to release all available memory back to cache. Try waiting awhile before saving. :)