Here's the initial announcement video with a timestamp where they called it the "worlds fastest CPU core". They've very quickly stopped using that as the tagline, but it was part of their initial marketing push.
https://youtu.be/5AwdkGKmZ0I?t=529
True, the text on screen did have that phrase without qualifiers, but what he actually said is: “…when it comes to low-power silicon, our high-performance core is the world’s fastest CPU core.”
