I have identified stuttering on two PCs caused by specific Windows updates

I have further narrowed down the issue!

After a lot of searching I have identified the specific cause of the stuttering, which is improper core parking. 

Upon inspection three of my eight CPU cores were parked while playing Battlefield 4, and I confirmed that my friend was experiencing the same issue.

We both use AMD FX8350 CPUs, and in both cases our cores were being improperly parked during gameplay resulting in abrupt, unprovoked FPS drops. 

It appears that in one of the Windows 7 updates between KB2758857 and KB2939576, the way Windows decides when and which cores to park, or perhaps how Windows communicates with applications was changed, resulting in Windows being unable to communicate properly with BF4.

The fix for the problem was very simple and involved downloading a third party application that disables Windows core parking.

The result is Battlefield 4 running perfectly again!

I have been unable to narrow down which of the updates specifically caused this issue, but if in any of those updates between KB2758857 and KB2939576 changes were made to the core parking algorithm Windows uses, that would be the culprit. It should be pretty trivial to patch in order to prevent this problem from happening to other people, or indeed if the same problem might be present in the upcoming Battlefield 1. 

I can provide more detailed system and driver information if necessary.