SUBSTANCE ENGINE

While that may be true, the more interesting question is why, it should be relatively straight forward for any cross platform dev to run a set of tests and determine that.
My guess would be some overhead from the hypervisor, or possibly some weird timing quirk with the bus.

In terms of compiler optimizations, the MS compiler is not particularly stellar, it does some things well, but others not so much.
Optimizing for modern processors is hard, and in some cases less that obvious, I recently saw a case where calling a function to increment a memory resident variable was faster than just incrementing it in line because the write is attempted speculatively by the processor which fails and has to be rescheduled the function call gives enough dead time for the write to succeed, so doesn't have the overhead of the reschedule and so runs faster.

 

Good observation

Hhmmm...

 

That's some pretty poor reasoning, IMO. If you have some particularly strong evidence proving that Microsoft's compiler generally produces faster-performing code on Jaguar, then you should provide it.

 

You forget the most probable cause: number of cores that games can use. 7 or 7.5 cores available for games with the PS4 versus 6 for X1 would easily explain the difference in the Substance test.

We have a hint with Battlefield 4 which has been announced taking advantage of 8 cores when I am sure on PC 8 cores are never available for games because one core (at least) must be reserved for the OS.

 

As far as I'm aware there is no specific core reservation for the OS on PC's. The OS simply uses as much or as little of the CPU as it requires. It's one of the advantages of not having a guaranteed performance level.

 

And one of the disadvantages is the OS can come along and take resources away causing stutters and framedrops in your game at random. The guaranteed service is an important part of the console experience which'll explain higher reservations that can be reduced over time.

 

Also depends on the Quality of the OS. With a mess like Vista that even slows itself down you would have to disable all the stuff you don`t want manually.

 

That's true but I'm just pointing out its not a win/win whichever option you go with - one has the potential for the OS to interfere with game performance and the other has the potential to waste CPU performance when the OS isn't using it.

That said, is it possible to manually reserve threads in Windows for specific tasks?

 

If by threads you mean a logical processor then I'm fairly sure that the Windows kernel does not support this. If you need guaranteed access to a processor right now then you can set your process thread priority class to REALTIME and it's priority level to TIME_CRITICAL and Windows will do the rest, including sidelining anything else with a lower priority.

However games generally do not run at higher [than NORMAL] priorities on Windows.

 

offtopic but you can change cpu affinity to all the running process and set cpu affinity to your thread to the cpu not used by other procecess