What is OpenGL?
It stands for Open Graphics Library. It is basically a set of functions that let you draw shapes on the screen. Many things you see today from games on the computer like Half-Life to Xbox and GameCube all use OpenGL. As of right now, it is forerunner of the graphics market.
Always, always cull. This elimnates 1/2 the geometry and reduces stress put on the video card.
Avoid State Changes
Avoid state changes (include glBegin and glEnd) as much as possible, as these are one of the slowest calls to make in OpenGL.
Always use display lists and vertex arrays (especially when using sin and cos with drawing circles and curves)
Library functions will always be faster than anything you can program. ALWAYS!
Frames Per Second
Keep in mind that an average monitor can usually display around 60 fps (frames per second), depending on the frequency its set to. This means that if your program is displaying 70 fps, then frames will be created and destroyed before your monitor can even display them.