I saw lag in one of the hands on videos showing the new lock screen. It's going to be there unless they fully re-optimize their software. Why they didn't with the 5th generation galaxy phone, I will never understand.
T-Mobile: Unlimited data, awesome pricing, WiFi Calling, and most importantly, FREEDOM to be able to use your phone as you want. DO NOT SUPPORT CARRIERS WHO LOCK BOOTLOADERS!
Current: Samsung Galaxy S5 G900T Charcoal Black