问GDI+ DrawImage在C++ (Win32)中明显慢于C# (WinForms)

EN

public Form1()
{
    this.SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer, true);
    this.image = Image.FromFile(...);
}

private readonly Image image;

protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);
    var sw = Stopwatch.StartNew();
    e.Graphics.TranslateTransform(this.translation.X, this.translation.Y); /* NOTE0 */
    e.Graphics.DrawImage(this.image, 0, 0, this.image.Width, this.image.Height);
    Debug.WriteLine(sw.Elapsed.TotalMilliseconds.ToString()); // ~3ms
}

// In wWinMain:
    Gdiplus::GdiplusStartupInput gdiplusStartupInput;
    Gdiplus::GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
    gdip_bitmap = Gdiplus::Image::FromFile(...);

// In the WndProc callback:
case WM_PAINT:
    // Need this for the back buffer bitmap
    RECT client_rect;
    GetClientRect(hWnd, &client_rect);
    int client_width = client_rect.right - client_rect.left;
    int client_height = client_rect.bottom - client_rect.top;

    // Double buffering
    HDC hdc0 = BeginPaint(hWnd, &ps);
    HDC hdc = CreateCompatibleDC(hdc0);
    HBITMAP back_buffer = CreateCompatibleBitmap(hdc0, client_width, client_height); /* NOTE1 */
    HBITMAP dummy_buffer = (HBITMAP)SelectObject(hdc, back_buffer);

    // Create GDI+ stuff on top of HDC
    Gdiplus::Graphics *graphics = Gdiplus::Graphics::FromHDC(hdc);

    QueryPerformanceCounter(...);
    graphics->DrawImage(gdip_bitmap, 0, 0, bitmap_width, bitmap_height);
    /* print performance counter diff */ // -> ~27 ms typically

    delete graphics;

    // Double buffering
    BitBlt(hdc0, 0, 0, client_width, client_height, hdc, 0, 0, SRCCOPY);
    SelectObject(hdc, dummy_buffer);
    DeleteObject(back_buffer);
    DeleteDC(hdc); // This is the temporary double buffer HDC

    EndPaint(hWnd, &ps);

bool bFillBitmapInfo(HDC hdc, BITMAPINFO *pbmi)
{
    HBITMAP hbm = NULL;
    bool bRet = false;

    // Create a dummy bitmap from which we can query color format info about the device surface.
    hbm = CreateCompatibleBitmap(hdc, 1, 1);

    pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);

    // Call first time to fill in BITMAPINFO header.
    GetDIBits(hdc, hbm, 0, 0, NULL, pbmi, DIB_RGB_COLORS);

    if ( pbmi->bmiHeader.biBitCount <= 8 ) {
        // UNSUPPORTED
    } else {
        if ( pbmi->bmiHeader.biCompression == BI_BITFIELDS ) {
            // Call a second time to get the color masks.
            // It's a GetDIBits Win32 "feature".
            GetDIBits(hdc, hbm, 0, pbmi->bmiHeader.biHeight, NULL, pbmi, DIB_RGB_COLORS);
        }
        bRet = true;
    }

    if (hbm != NULL) {
        DeleteObject(hbm);
        hbm = NULL;
    }
    return bRet;
}

HBITMAP CreateVeryCompatibleBitmap(HDC hdc, int width, int height)
{
    BITMAPINFO *pbmi = (BITMAPINFO *)LocalAlloc(LMEM_ZEROINIT, 4096); // Because otherwise I would have to figure out the actual size of the color table at the end; whatever...
    bFillBitmapInfo(hdc, pbmi);
    pbmi->bmiHeader.biWidth = width;
    pbmi->bmiHeader.biHeight = height;
    if (pbmi->bmiHeader.biCompression == BI_RGB) {
            pbmi->bmiHeader.biSizeImage = 0;
    } else {
        if ( pbmi->bmiHeader.biBitCount == 16 )
            pbmi->bmiHeader.biSizeImage = width * height * 2;
        else if ( pbmi->bmiHeader.biBitCount == 32 )
            pbmi->bmiHeader.biSizeImage = width * height * 4;
        else
            pbmi->bmiHeader.biSizeImage = 0;
    }
    pbmi->bmiHeader.biClrUsed = 0;
    pbmi->bmiHeader.biClrImportant = 0;

    void *dummy;
    HBITMAP back_buffer = CreateDIBSection(hdc, pbmi, DIB_RGB_COLORS, &dummy, NULL, 0);
    LocalFree(pbmi);
    return back_buffer;
}

if (better_bitmap == NULL)
{
    HBITMAP tmp_bitmap = CreateVeryCompatibleBitmap(hdc0, gdip_bitmap->GetWidth(), gdip_bitmap->GetHeight());
    HDC copy_hdc = CreateCompatibleDC(hdc0);
    HGDIOBJ old = SelectObject(copy_hdc, tmp_bitmap);
    Gdiplus::Graphics *copy_graphics = Gdiplus::Graphics::FromHDC(copy_hdc);
    copy_graphics->DrawImage(gdip_bitmap, 0, 0, gdip_bitmap->GetWidth(), gdip_bitmap->GetHeight());
    // Now tmp_bitmap contains the image, hopefully in the device's preferred format
    delete copy_graphics;
    SelectObject(copy_hdc, old);
    DeleteDC(copy_hdc);
    better_bitmap = Gdiplus::Bitmap::FromHBITMAP(tmp_bitmap, NULL);
}