Alpha mesh solution?

I while ago I posted a question to do with complex meshes having some of their subsets rendered with a semi-transparent texture - if other objects got placed inside the mesh, but rendered later on in the pipeline, the alpha bit was basically ignored effectively you couldn''t ''see'' through the windows. The thing is that I have a lot of different types of transparent things (I''ve got billboards, glass windows, particle effects... and some planar mesh features that rely on transparencies). To solve the problem for all of these various things, I am thinking of doing something like this: //Main Loop Declare an empty Cache RenderAllMeshes If a subset of a mesh has a transparent texture, don''t render the subset, but add its Type, Mesh, Position, Rotation and scale to the Cache. Update all billboards and add their Type, Texture, Position, Rotation and scale to the Cache Update all particles and add their Type, Texture, Position, Rotation and scale to the Cache Sort the Cache from Back To Front relative to the camera. For each Cache Entry, Check the type of entry (Mesh Subset/Particle/BB) and render it through the appropriate method. Anyway, I figure that this will work. I am already using the cache thing to handle Billboards and particles, so adding in mesh subsets as a type is no biggie. But, I am concerned that the re-rendering of mesh-subsets, with all those world transforms and stuff, will slow the code down too much. I could sort the entire mesh by depth, but there are issues with that, because contained objects would still get occluded. Does this seem like a worthwhile way forward, or is there a better way?