That GPU throttles both in Windows and OS X.
Anyone telling you otherwise is lying through their face. Either through ignorance or pig headed denial.
-and boy are there a lot of Apple apologists around here, you can practically hear them crawling through the woodwork whenever there's a genuine fault with an Apple product.
I owned that rotten stinker of a computer and I can bloody attest to just how god awful it is.
You want to see throttling in Windows, download GPU-Z and run anything even remotely demanding and you will see the GPU throttle almost instantly.
You want to see it in OS X, download Unigine Heaven and try running it at anything other that bare minimum.
You will clearly see the effects of heavy throttling.
Anyone denying the excessive throttling of the M370X is full of *****.
If you want a powerful and stable computer, don't buy a Pro with the M370X.
And there really is nothing more to say about it. End of story.
EDIT:
Do not believe those who post an "easy fix" to the throttling.
There is none.
Also, you might end up screwing your warrant to high heaven.
Trust me, I've tried, I desperately wanted it to work, it doesn't.
Once it gets hot, it WILL throttle.
So...better to go for the iGPU even if I have to do 3d modelling and video editing? I don't have computer right know, so I need one to work. Putting the same processor and 512GB is almost the same price than the one with dGPU...