Hey,

This is how my game loop looks like:

MSG msg;
ZeroMemory(&msg, sizeof(msg));

while(msg.message != WM_QUIT)
{
    if(PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    else
    {
        if( !Render() ) //In Render() function there are all game drawings and calculations 
        {
            MessageBox(NULL, "Failed to render", "Error", MB_OK | MB_ICONEXCLAMATION);
            PostQuitMessage(0);
        }

    }
}

I'm not actually sure what happens in PeekMessage(...) function. When the game window is active and has focus, everything seems to work fine. PeekMessage function seems to distribute CPU to my game in accordance with its needs. More CPU when there's collision, less when nothing happens at all. I experienced however huge growth of CPU when I minimize my window. I probably have dual core processor and thats why it's taking 50% CPU in that time.
When I erase this block of code from my game loop:

if(PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

it takes 50% of CPU all the time -> that's why I assumed that PeekMessage distributes somehow CPU. Simple infinite loop like this:

while(1)
{}

will also take 50% of CPU.

Why is that happening and how can I prevent this growth of CPU without sleep()? I would be very grateful for help!

Thanks for the answer. The problem is also that my game has multiplayer mode so I can't stall my application becouse client will timeout and disconnect from the server. Even if you say that programs run as fast as they can I still can't understand why my game doesn't use 50% of CPU all the time then? PeekMessage must be doing sth which prevents it from using max of CPU I guess.

Maybe your graphics card isn't able to accept more commands and your CPU is waiting for the GPU to finish?

Cheers!

It would be because it's a single threaded program and it max's out one core. if you have a dual core that's 50% usage on your CPU or one core with HT. That's the usual reason.

Thanks for answers! I think it's true that it was due to my lack of constant framerate. After adding some framerate the program no longer consumes max of 1 core's processor

You should empty the message queue every frame, not one message per frame.

MSG msg;

	while(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
	{
		if(msg.message == WM_QUIT)
			return false;

		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
if(g_Minimized)
Sleep(1);
 } else{
RenderFrame();

}

You can tell if window is minimized

switch(message)
{
case WM_SYSCOMMAND:
		switch (wParam)
		{          
			case SC_MINIMIZE:
				g_Minimized = true;
				return 0;
				break;
			default:
				return DefWindowProc(hWnd, message, wParam, lParam);
				break;
		}
}