Direct Composition has very high CPU and GPU usage

Question

I have a Direct Composition swap chain as the root visual of my window. I want to draw semi transparent custom controls over the swap chain, so I use an IDCompositionVirtualSurface as the content of a child visual and on every frame call IDCompositionSurface::BeginDraw() to obtain an ID2D1DeviceContext pointer, render the controls, then IDCompositionSurface::EndDraw() and IDCompositionDevice::Commit(). This however results in very high CPU and GPU usage (according to Task Manager rendering the controls with the swap chain directly typically uses ~2% CPU and ~0.5 GPU, the numbers easily go up to ~20% if the above method is used). Is this expected behavior? Is this the intended use case for Direct Composition? The rendering code looks like this:

ID2D1DeviceContext*   pDC;
IDXGISwapChain*       pSC;
IDCompositionSurface* pDCompSurface;
IDCompositionDevice*  pDCompDevice;
VOID OnPaint()
{
    POINT               pt;
    ID2D1DeviceContext* pDCompDC;

    pDC->BeginDraw();
    //Draw bottom content here with pDC
    pDCompSurface->BeginDraw(0, IID_PPV_ARGS(&pDCompDC), &pt);
    //Draw top content here with pDCompDC
    pDCompSurface->EndDraw();

    pDCompDC->Release();
    pDCompDevice->Commit();

    pDC->EndDraw();
    pSC->Present(1, 0);
}