Greater boat speed & wider angles
There's more luff projection to weather and twist (five to 10 degrees) in the Code Zero XC compared to a traditional Code Zero. The sail has a straighter, more stable leech and flatter exit, increasing drive in all conditions, but not overpowering the yacht in heavy-air reaching.
With the new design, there is less backwinding of the mainsail because there is less surplus material along the leech, which creates less drag when sailing close to the wind.