My read is that it's at 90% because they are saturating the CPU to that point with the TPS threshold they use for comparison, the TPS of Oriole is constant and way higher than pg in these charts at least.
I'd think the CPU will drop proportionally to the TPS, they just want to show how high it can go here.
Curious if it's a shift in design away from accounting for commercials interleaved every few minutes and now focusing on watching it all at once via streaming.