Ok, my iPhone 6 is showing it's age. Opening apps is slow, texting sometimes lags, and so on... Nevertheless, I can't say, I can find much sluggishness after an app or game launches. To test this, I've just installed the new Warhammer 40,000: Freeblade game, in my iPhone 6, and played for a while . All I can say is that it plays great. No noticeable hiccups or slowdowns. This was one of the games apple demoed at the 2017 keynote. Performance only concerning, is there any app or game that really makes you feel you have an outdated iPhone ?