ADF5355 Lock Time

Hi,

Currently my lock time is close to 8.5ms (ADIsimPLL reports 6.1ms for my loop filter config). I would like to improve this and expecting to bring it down. 

ADF5355 datasheet mentions that "Much faster lock times than those detailed in this data sheet are possible; contact Analog Devices for more information".
Any information about improving the lock times would be much appreciated.

Regards,

Anojh