Your application can use the IDirect3DDevice::Execute method to render primitives with or without automatic clipping. Using this method without clipping is always faster than setting the clipping flags because clipping tests during either the transformation or rasterization stages slow the process. If your application does not use automatic clipping, however, it must ensure that all of the rendering data is wholly within the viewing frustum. The best way to ensure this is to use simple bounding volumes for the models and transform these first. You can use the results of this first transformation to decide whether to wholly reject the data because all the data is outside the frustum, whether to use the no-clipping version of the IDirect3DDevice::Execute method because all the data is within the frustum, or whether to use the clipping flags because the data is partially within the frustum. In Immediate Mode it is possible to set up this sort of functionality within one execute buffer by using the flags in the D3DSTATUS structure and the D3DOP_BRANCHFORWARD member of the D3DOPCODE enumerated type to skip geometry when a bounding volume is outside the frustum. Direct3D's Retained Mode automatically uses these features to speed up its use of execute buffers.