In all fairness, based on what Moguri has said, it sounds like the slowness that you’re experiencing with OpenGL is specific to Intel’s OpenGL drivers. Between that and Intel integrated chipsets being (if I’m not much mistaken) relatively weak devices, I imagine that users with other chipsets might see better performance from OpenGL.
I am a little surprised–and disappointed in Intel–that you’re experiencing so great a difference in performance between OpenGL and DirectX, even given that you’re using an Intel integrated device.
For what it’s worth, I’m using OpenGL in my own projects, and feel that I’m seeing decent-enough performance, at least. However, I’m also doing so with an NVidia graphics card, and on what I think might be a slightly more-recent machine.