From my time working at a large UK airport where Security staff were employed directly by the airport: there were targets for the maximum length of time passengers spent in the queue for security checks. It was acknowledged that at busy times the target could be missed - this was known as a "breach". There was a limit to the number of breaches permitted each month, which if exceeded, resulted in a rebate being paid to the airlines using that terminal. The incentive was therefore on the terminal managers to deploy enough staff at key times (number of lanes open, sensible control of the queues) to contain the number of breaches within agreed levels.
There was no incentive or reward for security officers to speed up their checks, in fact there were several types of monitoring to ensure that things were done "by the book".