Windows 7 Basic Theme “frame lag” of some kind

Question

I have been having a problem with my computer(laptop) when using the Windows 7 Ultimate Basic Theme.
The problem I'm having is that, whenever this theme is active, and I move one window over another, I get this "frame lag". That's as close as I can describe it, here is a screenshot:

The amount of frame of the application that it "lags" onto the underlying application varies. As an example: When I'm using 2 notepad Windows, there's only a tiny bit of frames that get left behind, and when any window is moving over and Explorer window, it's a lot of frames. The "left-behind" frames clear every .8 seconds or so, which also constantly varies between programs.

This only happens on the basic theme. Works fine with Aero. My video card is perfectly capable of rendering this. I can run Crysis just fine. It's an nVidia 9600M GS with 512MB of RAM (M ofcourse meaning "mobility" as it's in a laptop.). I currently aslo have 2 FullHD monitors connected, but it also happens on the native laptop screen with a moderate resolution of 1440 x 900. All the latest nVidia drivers have been installed.

Answer 1

What you are experiencing is called "window tearing". It's a phenomenon that occurs on Windows Basic theme only, due to the absense of Windows Aero.

Aero uses the DWM (Desktop Window Manager) introduced in Windows Vista, which is much more closely bound to the graphics card and hardware acceleration, compared to using the computer without DWM.

This means that while Aero actually looks better, a much higher percentage of it is rendered by the GPU, and not the CPU. In the Windows Basic theme, much of the screen is software accelerated, by individually sending the WM_PAINT message to all applications.

Now, furthermore, DWM uses double-buffering to prevent flickering and Window tearing.

Wikipedia states:

Since MIL provides a retained mode graphics system by caching the composition trees, the job of repainting and refreshing the screen when windows are moved is handled by DWM and MIL, freeing the application of the responsibility. The background data is already in the composition tree and the off-screen buffers, that is directly used to render the background, without having the background applications to re-render themselves by sending them the WM_PAINT message, as was the case with pre-Vista Windows OSs. DWM uses double-buffered graphics to prevent flickering and tearing during window moves. The compositing engine uses optimizations such as culling to improve performance, as well as not redrawing areas that haven't changed. Because the compositor is multi-monitor aware, the DWM natively supports that too.

Now, my theory of why it is happening is not because of the GPU. It's because of your CPU. If having multiple monitors connected in Windows Basic theme, then depending on your graphics cards performance, using Aero may actually be faster.