Source: http://gamingbolt.com/devs-react-to-dx-12-doubling-xbox-one-gpu-speed-ps4-ice-programmer-be-suspicious-of-claims

As i said before, we know DX12 is going to help improve XBO's performance, that is a given. For the people who acts like it isnt going to do anything are just as bad as the people who are acting like it is the best thing ever. Not talking about the people in this article, rather the fans which is most likely a cause of a console war.  It works both ways.  Dont act like its going to make it a magical box and dont act like it isnt going to do anything either.  Its not natural progression, it is advancing tech and tools that will help improve the console.  Why anybody should be upset with that is beyond me.  This whole topic has become overblown by this point

I'm with Billy O'Neal. The CPUs in both consoles are just "meh" at best.

At any rate, this sounds like the usual Blast Processing style politicking we always see when it comes to new consoles. We'll know whether or not any of this checks out over time.

Well 2x is a joke from beggining unless the software was fucked on Xone and Ryse can't be done with a fucked software...

About DX12 it obvious that it will improve performance of the CPU use in games... MS says in best cases (theses hypothetical) 50% in multi-core utilization... but overall you will see some 10% to 20% improvement in real games... this is a huge improvement with optimizations.

BTW the guy tha said that it will doubles the performance could have made a bad code from start and after optimizations and bug fix... plus DX12... ended with double performance in his tests.

Billy give the best comment...

I agree... consoles always used to be like what DX12 is finally trying to match... even PC in the past was more close to metal (ohhhhh the old and amazing Glide)...

The API are facing now that they need to back to the old model to extract more from the hardware... good times when a weak CPU/GPU did miracles for the bullets it had...

Haha the PS4 programmer says to be suspicious.

Also, the president of Nintendo says 'Please understand.'

Besides, his comments weren't even that negative.

Console API's always get better with time. DX12 is progression. this is why games got better last gen with time and this gen is no different. Xbone performance gain due to better tools is expected with time and is not limited to only the xbone. Wii U tools will get better too, so will ps4's. The "war" is caused by xbone fans thinking only the xbone will improve in time because of DX12, when its normal for all console api's to get better. The people who should rightfully rejoice the most are actually PC gamers as low level access to hardware will actually benefit them the most.

This is how it is: Powerful PCs will always do graphics better. DX12 will even increase the gap between PC and Consoles.
Anything the Xbone will be able to do due to DX12, will be done [better] on the PS4 too as the PS4 api advances.

So at what percentage do you stand? And what percentage would be insignificant enough to call it "nothing"?

I stand at what i said. It will improve the console and PC.  It has been praised since its announcement and it is obvious there is going to be improvements.  As far as the numbers games and at what percent does not matter to me.  If it doubles, cool.  If it doesnt, that is fine too. I In the end it is going to improve things from where they are now. 

I dont need a programmers to tell me to be suspicious. Its an outrageous claim.

That is why my answer to it is: show it, dont preach it.