I agree that it is software. My first 6S Plus purchased launch weekend, had this lag/freeze issue, but after a few days, it went away and everything worked smoothly. Recently purchased a sim-free 6S Plus, installed 9.1 and do have this lag/freeze effect but I'm going to keep an eye for a week, i'm pretty sure it will go away as it did with my previous 6S Plus.How do you explain how the lag magically disappears after a few days? It's software...
*Not to mention that my current one is TSMC chip.