Ok, but was he kicking and screaming about fuel consumption? He has certainly made a lot of noise about delivery delays and cabin quality control issues, as have other airlines, but there are no media reports about performance issues.
We have had no issues with the aircraft not meeting its performance specs. Indeed, as I said above, the aircraft's speed schedule is set to be modified because the aircraft is more efficient at a slightly higher speed than it has been operating to date.
Consider some figures from a couple of today's long haul flights to the same destination, one operated by a B777-300ER and the other by an A350-900. The revenue payload carried by the aircraft on these flights was almost the same. The B777 only carried about 500kg more payload, but it burnt almost 19 tonnes more fuel than the A359.