I have the same issue with my 7470M. It is actually not a BIOS problem or relevant to that link above. dGPU or dynamic GPU is also not the issue, turning it off doesn't fix the problem.
Simply, there's a bug that halves the discrete GPU performance if you were to do nothing special after the computer starts up.
How I worked this around basically was to go to
- Hit F10 (right when u power up) to enter the BIOS
- Switch graphical mode from Dynamic to fixed in the config tab, save the settings
- (Optional Tweak) Toggle Function Fn keys
- Action keys mode
- Disabled and save it
- Boot up the computer
- Switchable Graphics
- Select Power saving GPU, let it enter that mode
- After it uses the Intel HD, switch back to high performance GPU
- Now if you were to run a benchmark like Windows Experience Index, your GPU performance should hit about 6.5-6.7.
The performance will stop halving but you'll have to do this 90% of the times you start up the PC. For me, updating to CCC 12.6 and using an SSD has helped the issue slightly but still, most of the startups result in the GPU halving performance.
So far I've tried every other fanciful thing with ccc, various methods of uninstalling and so, nothing helps. Only the workaround did help.