mutt
It seems to be a problem unique to VS, and may have something to do with the heavy seats and other kit they've installed in the forward cabin. This has led to an unfortunate nose-heavy condition, which in turn has had a negative effect on fuel-burn and the amount of cargo that can be carried in the FWD lower-deck.
Had a guy from VS and a lady from LH at a meeting recently, where the VS bloke raised this issue and asked if LH had experienced similar problems. The answer was a resounding "no, we're extremely happy with the performance of the aircraft - in fact it's slightly better than what Airbus promised us".