The firmware in a 2k servo verifies the position of the servo arm two thousand times each second, 
while the firmware found in previous servos verify the arm's position one thousand times per second.
This greater number of verifications makes for a very precise servo, and gives it a more "solid" feel.

It is recommended to use a booster cable with 2k servos to ensure steady voltage at all times.

8911BL 2K