>What kind or ancient arm hardware are they using here?
I think that's the point being made here. ARM in the 2000s was not known to be fast, now it is.
RISC-V being slow isn't an inherent characteristic of the ISA, it only tells you about the quality of its implementations. And said implementations will only improve if corporations are throwing capitals at it (see: Apple, Qualcomm, etc.)
I think standard Arm cores are already plenty fast, the issue is the SoC vendors are still using cortex-A57 from 2015 instead of the new designs.