I’m using a VBO in conjunction with a vertex program. Initially the rendering is very slow ( slower than using glVertex calls ) but after rotating the object around awhile the performance will suddenly and dramatically improve.
As I mentioned, performance is OK when using the vertex program in conjunction w/ glVertex calls instead of using the VBO. So, at least for now, I think the problem lies in how I’m using VBO’s and not the vertex program.
are you using a dual core machine? I had the same issues on a Laptop with Centrino Duo and NVidia 7950 GTX graphics card. Apparently this has something to do with the NVidia drivers running on a dual core machine.
I did some research and monitored fps over time. Interestingly, the slowdown is affecting only the first 120 frames or so. My workaround was to render 200 frames right after opengl context creation (just glClear, gluLookAt and glFlush). Performance is back to normal after doing this.