This was cut from EVE's wiki

Sensor Recalibration Delay
(page 10)
The sensor recalibration delay is a delay after decloaking in which you cannot target-lock anything. The time varies with ships and types of cloak, and is affected by your skill level in Cloaking. This penalty is what is reduced by faction and officer versions of cloaking devices. The table on page 10 shows all sensor recalibration delays, again I forgot to include Blockade Runners - they have the same delay as Force Recon ships.
This penalty is probably one of the biggest things to know about being cloaked - you cannot decloak and immediately point someone, unless you fly the right ship. There will always be a delay while your sensors are recalibrating until you can start to target-lock your target. As an example, remember you need your Cloaking skill at level four to fit a CovOps cloak. So in your covert ops frigate, force recon or cloaky Tech 3, you will have a sensor recalibration delay time of 6 seconds. You can decrease that by one second, to a 5 second delay if you train Cloaking to level five. That one second can make a difference between catching your target, and missing it.

I would like to see a delay after decloaking in Dust!! And if you train long and hard enough and can afford the suit you can reduce it to the point where you can decloaking and insta kill