That's true. Actually most iPhones outperform their competitors. Apple tends to make better decisions, like not going overboard with resolution(pushing 1080P instead of wasting performance on 1440P) until the hardware is more than capable. That coupled with having a better optimized OS.
1) The hardware is perfectly capable. Any lag when using 1440p screens is the result of OEM and carrier bloat. My S7 runs smooth as shit and I have the worse performing S820 version.
2) They aren't wasting performance. This high res screen is primarily for VR, so it's necessary. I'll give you the benefit of the doubt and assume you had no idea because I didn't as well when I critizied that high resolution.
Also, LMAO to all those are willingly being ignorant about AMOLED screen tech on phones today. It's like you have your fingers you ears while screamingly "LALALALA!" It's pretty embarrassing.