Alleycat - the old Bryce trees used crappy trans-maps but the new ones do not. There are no transparencies in the materials used for them. It is true that all trees increase render time, and it is also very true that poly trees cause more rays to be traced due to all the odd angle polygons that reflect light in every direction. Some of the bryce 'preset' trees have refraction set but this is not necessary since they have no transparency. The only time trans-maps are used on the new b5 trees is when you go for a user leaf - all the other leaf shapes already have the right shape and can use simple DTE materials with no transparency.