[RESOLVED] What is the fastest rendering method?

What is the quickest way to draw something in c++?
I mean, let's say i have created a window, and now i want to draw something on it. It doesn't have to be sprites with textures. Just squares with colors is good enough.

I've heard about OpenGL and DirectX11, but i don't know which one is faster.

For those of you wondering why i need to know this, i am programming a galaxy collision simulator, and when rendering all the particles i need to draw all particles as quick as possible or it will lag ALOT. I first wrote this program in visual basic and it rendered with DirectX 8. But that was is wayyyy to slow. So now i'm learning C++ and hope that it will operate faster than visual basic.

tl;dr: What is the fastest rendering method?

I am not convinced that the rendering will be the bottleneck in a collision simulator.
I know for a fact that former VBF member timeshifter has written some pretty nifty particle physics rendering applications in C# and GDI+, running at a good amount of frames per second.

Anyway, as for D3D vs OpenGL, there won't be any noticeable difference. What you choose can depend on a number of other factors:
Do you need to compile cross-platform or just for Windows?
Do you have any use for the extra features that DirectX provides? OpenGL is just a rendering library whereas DX11 is more than that.
Are you familiar with any of the two already? You mention you have used DX8. This alone can be a reason to go with DX11 instead of OpenGL, as OpenGL is very different to use.