Though I agree that most single sites wont benefit from this. We have a single site serving 100 pages/sec and php is not even close to becoming a bottleneck.

Though I agree that most single sites wont benefit from this. We have a single site serving 100 pages/sec and php is not even close to becoming a bottleneck. The other application where this may be helpful is the cloud. In a system like this you have 100s or 1000s of sites on a single machine that may reach the combined traffic where this optimization can come into play.