DirectX framework performance issue - c++

Question

After continuously capture mouse input ie. left and right click, the pc will become very lag when switching to another software such as Google Chrome but when you end the framework for few seconds will back to normal with no lag.
The framework works fine until I create Graphics object. So, I doubt there is something wrong with Graphics class but I still cannot find out which part cause this performance issue.
Graphics class
Graphics.h
#ifndef GRAPHICS_H
#define GRAPHICS_H
#include <d3d9.h>
class Graphics
{
public:
Graphics();
~Graphics();
void initialize(HWND hWnd, int backBufferWidth, int backBufferHeight);
void BeginFrame();
void EndFrame();
private:
IDirect3D9* direct3D9;
IDirect3DDevice9* d3dDevice;
};
#endif
Graphics.cpp
#include "Graphics.h"
Graphics::Graphics()
{
}
Graphics::~Graphics()
{
// Release the device when exiting.
d3dDevice->Release();
// Reset pointer to NULL.
d3dDevice = NULL;
}
void Graphics::initialize(HWND hWnd, int backBufferWidth, int backBufferHeight)
{
// Define Direct3D 9.
direct3D9 = Direct3DCreate9(D3D_SDK_VERSION);
// Define how the screen presents.
D3DPRESENT_PARAMETERS d3dPP;
ZeroMemory(&d3dPP, sizeof(d3dPP));
d3dPP.Windowed = true;
d3dPP.SwapEffect = D3DSWAPEFFECT_DISCARD;
d3dPP.BackBufferFormat = D3DFMT_X8R8G8B8;
d3dPP.BackBufferCount = 1;
d3dPP.BackBufferWidth = backBufferWidth;
d3dPP.BackBufferHeight = backBufferHeight;
d3dPP.hDeviceWindow = hWnd;
// Create a Direct3D 9 device.
direct3D9->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,
D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dPP, &d3dDevice);
}
void Graphics::BeginFrame()
{
// Clear the back buffer.
d3dDevice->Clear(0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
// Begin the scene
d3dDevice->BeginScene();
}
void Graphics::EndFrame()
{
// End the scene
d3dDevice->EndScene();
// Present the back buffer to screen
d3dDevice->Present(NULL, NULL, NULL, NULL);
}
Here is my whole project if you want to check all the codes : https://www.dropbox.com/s/p4nm57fzqse12t7/Zero%20DirectX%20Framework.rar