DirectX isn't widely used or supported. DirectX 9 is used on the XBox 360, and for a lot of Windows games. DirectX 10 is supported on Windows Vista and 7, and used in very few games. DirectX 11 is used in maybe three games, and only runs on Vista and 7.
OpenGL has the same features as DirectX, runs on Windows XP, Vista, 7, Mac, Linux, Wii, iPhone, and PS3, and doesn't change every three years. A few years ago the choice to use OpenGL was made more out of convenience, but now it is clear that OpenGL is a better API to use. OpenGL even supports Windows better than DirectX does.
If you have a bug report please post it in the bug tracker. If you have a question about performance with a specific application please post an example so we can try it ourselves.