Is it OK, (work and no loss of performance) to Lock a Vertex Buffer, loop througth your objects (some write to it) and the other render from another VB. ex.: vbA.Lock(); Write stuff to vbA SetStreamSource(vbB) DrawPrimitive(...); Write stuff to vbA vbA.Unlock SetStreamSource(vbA) DrawPrimitive(...); Will i lose any performance ?