((me->flag&ME_SUBSURF) && me->subdiv) In build_mesh_data(). This because meshes with subdiv==0 were calling a MakeDisplist() for each redraw otherwise, disabling for example the posemode "delay deform" feature. (bug #2700) Daniel; it would help if you would add comments in the code, for example to understand the difference between; mesh_get_base_derived() mesh_get_derived() and how it relates to build_mesh_data() I realize most of the mess is in displist code... and confusing use of features while editing, posemode, & render. Nevertheless, it's not clear at first sight which parts of derivedmesh is design, and which part reflects the hacks to make it work. :)