Please see this thread on performance degradation which has over 2,600 posts. It’s a widespread problem.
And therein lies the problem. They can’t reproduce it, so they can’t track it down. In my opinion, they need to work harder to reproduce it then. It clearly affects tons of PC users, so if they can’t replicate it in house, they need to start thinking outside of the box to figure out ways to replicate it so they can track it down.