It's "Cost per task", so perhaps it burns tokens too quickly, trying to "do a better job". Over-engineering :)

Last week it felt like Opus 4.8 was moving the Pro "usage" meter very quickly. Today, pre-announcement, Opus 4.8 Medium felt like there was less meter-use per minute. And post-announcement, Opus 5 Medium also feels more efficient, allowing more work in the 5-hour window.

Completely subjective, of course.