I've got an AMD 6750M graphics card with 1 GB of VRAM and Blender 2.79. I successfully selected the card as a GPU target in the user preferences.
When starting my render, Blender says:
Loading render kernels
According to Activity Monitor a process named CVMCompiler has now been running for over five hours. That surely is more than a few minutes?
The rest of macOS is practically unusable, as it seems most things are reliant on the GPU. When I force quit the process, other apps, including Safari, become responsive immediately.
What could be the issue? I can't see any signs of any errors, but where should I look to find any?