VBO doesn't work

I thought that, when i'll turn VBO i will have more fps

What I expected to happen was...:
When i turned VBO on, I expected that I would have more fps

What actually happened was...:
Instead it, I had the same number of fps like before turning VBO on

Steps to Reproduce:
1. Look on number of fps at F3
2. Turn VBO on
3. Look at F3 again. It didn't change