[smaudet]

"While the summary in this reply is at best misleading if not simply wrong" - only if you take the summary too literally.

Slow-downs of up to at least 30% did in fact occur (with the older hardware): https://www.techradar.com/news/more-details-emerge-on-how-mu...

As for assuming access and tricking into execution of what you wanted, branching forms the foundation for many if not all OS level security features, in the form of boolean flags, bits behind protected memory (protected by more branching), etc. If the result of a compare causes code to execute that should not (for security reasons), then you have caused execution of what you wanted, which can lead to exposure of e.g. operating system secrets. And with such access it then becomes (sometimes) possible to executing more of what you wanted.

I.e. trusted code could be used to cause insecure results.

Oversimplification, sure, but the truth (exposure of register results due to fault of the hardware) is overly technical and under-emphasizes the severity of the issue, so it is somewhat intentionally misleading...