Ja, es existiert eine Begrenzung. Man kann sie über D3DCAPSx unter MaxPrimitiveCount ermitteln:
MaxPointSize Maximum size of a point primitive. If set to 1.0f then device does not support point size control. The range is greater than or equal to 1.0f. MaxPrimitiveCount Maximum number of primitives, or vertices for each DrawPrimitive call. Note that when Direct3D is working with a DirectX 6.0 or DirectX 7.0 driver, this field is set to 0xFFFF. This means that not only the number of primitives but also the number of vertices is limited by this value. MaxVertexIndex Maximum size of indices supported for hardware vertex processing. It is possible to create 32-bit index buffers by specifying D3DFMT_INDEX32; however, you will not be able to render with the index buffer unless this value is greater than 0x0000FFFF.