I've been using DrawArrays to draw several objects. I realized that many of these objects have common vertices, so I cerated a single VBO with all possible vertices (~80K), then used drawelements. I expected a slight increase in performance from reduced data transfer. What I got is over a 50% decrease in FPS. I tried the same code on two other computers. One showed no difference, the other had a 25% increase in FPS.
Here are the computer stats:
Comp #1 (50% decrease)
Win 7 32-bit, ATI Radeon HD 4300, OpenGL v. 3.3 Comparability Profile Context
Comp #2 (25% increase)
Vista 64-bit, NVIDIA Quadro FX 2700M, OpenGL v. 2.1.
Comp #3 (no difference)
Win 7 64-bit, Mobile Intel 4 Series Express Chipset Family, OpenGL v. 2.1
I'm not surprised #3 had no difference since its integrated graphics, but why #1 got worse and #2 got better with the same code is beyond me. I suspect its a driver issue, but I can't find anyone with a similar card and these problems.