I read an article yesterday at opengl.org that the most expensive call is in VBOs. Now I tried again to find the article but couldn't. If I remember it said that VBOs were the most expensive and then state changes. I'm trying to work out what it meant by VBO's being expensive: a) chucking the arays onto the GPU memory b) telling the grfx card to use a different vbo c) changing data in the vbo Thanks Ade

glBufferDataARB() is certainly the most expensive routine for VBO's

yes, the function is expensive because it peforms the upload.

In the case of the others for using a VBO it depends on the driver, NV and ATI do setup in different places iirc.

Mapping a VBO can cause you stalls, unless handled properly this should be avoided.