Using Discrete graphic

Less advantageous for you if you just web browse. nvidia will use more power and drain batter quicker. If you're running more graphic intensive things, itll automatically switch to nvidia since the intel wont be able to handle it

 

if you manually turn off the integrated graphics in the energy saver tab then the system is force to use discrete graphics all the time. for mild usage it will just hog up battery juice.
naturally, nvidia optimus will use discrete graphics when system process idles to extend battery life, and switches to discrete graphic processing when a demanding load requires it. like video games or photoshop or auto cad or the likes. that's what the discrete video chip is there for.
although nvidia driver will down clock the GPU while video processing is at idle, but i wouldn't advise running it all the time as it's just hogs energy.

 

Can you clarify that a bit....I would imagine it would have to be able to handle anything with the integrated card as the 13 inch only has an integrated card. So why wouldn't the 15 inch be able to handle anything with it's integrated card? It's the same card isn't it? Unless I'm missing something. Wouldn't the discrete just speed everything up and make it smoother?

 

Some people use their macbooks for graphic intensive tasks like gaming. The intel HD 4000 may handle many games but will certainly not handle all of them.