My 3635QM throttles to 2.35Ghz when running distributed computing on the CPU and the laptop dGPU at the same time. The GPU doesn't throttle when the CPU and GPU are 99% loaded simultaneously.
In fact, if I only run PrimeGrid/Seti@Home on the CPU, I am often in the 3.19-3.3Ghz range, but as soon as I add the GPU into the mix for other projects, my CPU speed on all 8 threads falls below the 2.4Ghz base clock.
I never paid attention to Intel's base clock since on my desktop I always had sufficient cooling. For my next laptop upgrade, I will pay extra $100-200 to get a chip with a much higher base clock. The CPU temperature does not exceed 94C, which is way below 105C maximum the 3635QM is rated at.
In practice that means for my laptop usage a 2.8Ghz Intel i7 with a 4.0Ghz Turbo would not be just 18% faster than a 2.2Ghz i7 that with a 3.4Ghz Turbo, but actually 27%!
The programs I run aren't even synthetic like Furmark/Prime95. If I tried those, it would be disastrous. I bet my 3635 would drop to 1.8-2Ghz.
If you read Notebookcheck wrt max load data on even the best Intel laptops, when loading the CPU and GPU to 99% similtaneously, you will almost always get CPU or GPU throttling or both. For example, the 970 SLI Aorus X7 will for sure throttle the i7 under such a scenario. The few laptops that might cope better are 9-12 lbs bricks with 1.7-2.2 inch thickness and 1.5 hour or less battery life. I don't consider those products 'laptops'.