I mean my "No it isn't, it has a fixed number of yields, which has a very different duration on various CPUs" can be verified directly by having a look at the table in my article showing different timings for pause.

For the yield part, I already linked to the part that shows that. Yes it doesn't call yield if it sees others are parked, but on quick lock/unlock of threads it happens that it sees nobody parked and fails, yielding directly to the OS. This is not frequent, but frequent enough that it can introduce delay issues.