From version 14.8 the Cycles render engine will be turned on as the default render engine to use when generating a High Quality Render. It takes advantage of your GPU and will leave the CPU free for design tasks and system responsiveness. Cycles delivers crisper materials, truer lighting, and more realistic whites addressing the key pain points highlighted during user feedback.
Using GPU for Cycles and CPU for Real-time camera movement
If you have previously turned off hardware acceleration, you may have noticed that it also disabled acceleration for real-time camera movement and the Cycles engine. From version 14.8 we have added a new option: Enabled for HQ only in Preferences > Rendering. By selecting this from the dropdown menu next to Hardware Acceleration, you can keep your real-time camera movement running on the CPU while leveraging the GPU for Cycles renders. For more information click here.
Note: the recommended selection is Enabled