The term latency defines as response time — the time that elapses between a stimulus and the response to it. Touchscreen latency for a smartphone is the time lag between an input on the screen and the device reacting to it. That means how responsive an application feels on a mobile device from the time the user feels that they’ve touched the device’s display to the time the user sees a response on the screen. Every few milliseconds of latency reduces the responsiveness of the app being streamed.
In a touchscreen latency test conducted by a 15 member team of the company called Agawi by introducing a custom built measurement device called Touchscope. They performed the test using a combination of high frame rate cameras capturing at 240fps and Touchscope to accurately measure the App Response Time (ART).
Under the question, “Are Apple’s touchscreens more responsive than Android and WP8 devices”, they perform the touchscreen latency test of flagship smartphones from top manufacturers. They compared the iPhone 5, the iPhone 4, the Galaxy S4, the Lumia 928, the HTC One and the Moto X. Here are the results:
The results are remarkable, The iPhone 5 is twice as responsive as any Android or WP8 phone tested, even iPhone 4 has the edge over rivals like S4, HTC One. The closets rival in the latency test is the Galaxy S4, with over twice the latency. According to the above performed test the iOS devices feel much smoother and responsive than Android and Windows Phone 8 devices.
We never found the touchscreen responsive time measure of a device in a specs sheet or in any comparison charts but this is the one thing that matters a lot with the performance of the device.[Source]