> More importantly, the CPU usage percentages reported by ps have fallen
That's not a meaningful comparison when the CPU itself is running at a higher frequency. Lower frequency enables the CPU to waste less effort, e.g. while waiting on memory or I/O.
I don’t know if the same holds true in servers, but in mobile you want to race to idle. In other words, consistent high CPU usage at a low frequency is worse than spiking the frequency up to get CPU usage down to 0. I would imagine that holds too although it’s more complicated because a server usage model is different (perhaps a constant baseload to begin with changes the calculus).
Race to idle is good in a compute heavy workload (up to thermal limits), but I'm not sure it is when the CPU is mostly waiting for memory. Also IIRC, the point of using "performance" in the first place is that it keeps the CPU at its design frequency even when idle - so it will be less able to boost further when needed.
That's not a meaningful comparison when the CPU itself is running at a higher frequency. Lower frequency enables the CPU to waste less effort, e.g. while waiting on memory or I/O.