It depends on many things, what are the specs on your computer. What are you Minecraft settings. A couple of things it could be. Sometimes AMD cards go berserk with the Minecraft mipmapping, turn that off, it shouldn't matter for NVidia cards from what I know.....
It could also be that your settings are still just to high.
It might also be that Java is running entirely off the CPU, this happens because the computer doesn't recognise Minecraft as a game, and Java is usually used for small tasks. If you are using a NVidia GPU, try going to the control panel -> Manage 3D Settings -> Program Settings -> Add, then select Java... if you have recently closed MC it will be there, otherwise, just search for it..... Once you add it click apply...