The A330 manual says that if you fly an Approach at Vapp ( VRef ) then cross the threshold at 50', Flare at 40' ( 2 to 3 deg nose up ) and then smoothly close the Thrust Levers you will lose around 5 kts during the flare manoeuvre. All quite ok.
It goes on to say:-
FACTORS AFFECTING LANDING DISTANCE
The field length requirements are contained in the Landing Performance section of FCOM 2. The landing distance margin is reduced if the correct landing technique is not used. Factors that affect stopping distance include:
• Height and speed over the threshold
• Glideslope angle
• Landing flare technique
• Delay in lowering the nose onto the runway
• Improper use of available deceleration devices
• Runway conditions (discussed in adverse weather)
Height of the aircraft over the runway threshold has a significant effect on total landing distance. For example, on a 3° glide path, passing over the runway threshold at 100 ft rather than 50 ft could increase the total landing distance by approximately 300 m/950 ft. This is due to the length of runway used before the aircraft touches down.
A 5 kt speed increment on VAPP will result in a 5% increase to the distance extracted from the 'Landing Distance with Autobrake' table in the QRH.
A prolonged period of level flight above the runway prior to touchdown must be avoided as it uses a significant amount of the runway length available. Land the aircraft as near to the normal touchdown point as possible. Deceleration on the runway is approximately three times greater than in the air.
The minimum stopping distance is achieved by applying maximum manual antiskid braking with maximum reverse thrust selected and ground spoilers fully deployed.