I was JUST about to create a post about this lag. Something is definitely not right to have lag delays for so long. I was going to say it's probably the ram in our 3gb model but I have two work phones running on 2gb ram and never got lag this bad.
When it just freezes with lag (at random even if I haven't used the phone for an while), I check the ram and there is still 1.5gb free so it's not a ram issue, must be a software issue. A few times a day it'll take an app a full 60-90 seconds to launch and everything will be at a snails pace for the next 5 minutes. If anyone has any tips it'll GREATLY be appreciated.