Most laptops have features that throttle down both the GPU and the CPU when you run on battery in order to save power. For the CPU, the feature is called speedstep for Intel CPUs. You have to go into the BIOS to disable this feature. For your GPU since it's a NVidia card, you'd most likely have to go into the NV control panel and either look for power settings or a section called PowerMizer.
Note: your battery life will drop like a rock since both the CPU and GPU will run full tilt.