TLDR: The response time of a display measures how quickly a pixel can change from one color to another. Standard figures are in the neighborhood for 4ms for IPS panels, and 1ms for TN panels. Faster response times are more desirable, but this is mostly a gamer-feature to improve the image fidelity. Most casual users probably won’t see feel a difference.
Response time is related to, but separate from, input lag. Anytime you hit your mouse button, there’s a delay between how long it takes that click to make it to your screen. In other words, your hardware sends a signal to your computer, and your computer sends a signal to your screen, but how fast that signal gets received and displayed is another thing entirely.
Response times are measured in miliseconds. If you’re using a 60hz monitor, that means your screen is refreshing 60 times per second, so response times need to be small and precise. Longer response times lead to what people call ghosting, which is the appearance of trails from a moving object because the pixels behind aren’t fast enough at refreshing.
Normal Response Times
Typical values you’ll see on monitors range from 5-12ms. Anything around 5ms is somewhat standard for 2017. Faster response times are available mostly in gaming- ultrawide monitors, because response times are a feature mostly gamers are interested in. For gamers, 1ms response time is the golden standard. It helps ensure that even when you’ve got the speed of a high refresh rate and FPS, your screen remains crystal clear and blur-free.
Should you break your bank going after a better extra response time? The answer is generally no. It’s an excellent feature to have, but apart from some competitive gamers who want perfect image fidelity, most people won’t need a top-shelf response time. For those who do have the extra cash to access a top-shelf feature like 1ms response time, you can hardly do better than a well-rounded gaming ultrawide like the Asus ROG PG348Q, which has a 100Hz refresh rate and G-Sync.
The Long and Short of It
Response time can have a significant visual impact when it comes to fast-action. That means if you’re playing competitive FTS games, this is something that should concern you. If you’re all-about the immersion, which is one of the benefits of an ultrawide, 1ms ultrawide monitors will help keep your screen crystal clear no matter how fast things keep going. But if you’re browsing Facebook, watching movies, working, and playing casual or slow-paced games, it’s not something you have to think about.