A google trends search for "iphone slow" returns a graph with humps representing iphone releases. They're claiming its only been happening since iOS 10.

Found it!

Dear customers,

Our early customers trusted us, and we must live up to that trust with our actions in moments like these.

We have decided to offer every iPhone customer who purchased an iPhone from either Apple or AT&T, and who is not receiving a rebate or any other consideration, a $100 store credit towards the purchase of any product at an Apple Retail Store or the Apple Online Store. Details are still being worked out and will be posted on Apple's website next week. Stay tuned.

We want to do the right thing for our valued iPhone customers. We apologize for disappointing some of you, and we are doing our best to live up to your high expectations of Apple.

Steve Jobs 
Apple CEO
/r/conspiracy Thread Parent Link - i.imgur.com