Here’s a really annoying one. Dell XPS and Alienware machines, despite their significant capabilities, experience super slow high-res video streaming on YouTube. The buffer is visibly razor-thin on anything 1080p or above without any obvious reason why. This occurred on a gigabit fiber connection in my case.
The solution? As often is the case, the value-added (in this case, QoS traffic-shaping/packet inspection) networking software is actually value-subtracted. Simply navigate to the Killer Control Center software and disable the following (useless) option to correct the problem and reclaim your proper streaming speeds!