To set the world rotation of an object to <r, p, y> requires creation and multiplication of three rotations. These objects, being four cells, all go on the heap.

If ll>SetLinkPrimitiveParamsFast had, e.g. PRIM_ROT_FROM_RPY, <r,p,y>, the entire operation could be done using vectors, which live on the stack. For objects that adjust their position and rotation frequently, trains, etc., the savings in garbage creation would be substantial.

Thanks!