Text messages are coming in about 30 minutes to an hour late

So as soon as I updated my phone to iOS 9 noticed my texts were coming in 30 minutes to an hour late every time the screen is locked (not being used) but when it's unlocked and just sitting at the home I get my messages on time with no delay and get a notification every time where as when it's locked I do not get notification or sound. phone is also very laggy, sluggish, gets extremely hot, and just has its own glitches here and there. But, my main concern is with my text messages coming in late considering my boss texts me to let me know what's going on for the day, to switch to another job, go get things, etc. If you're having the same problem please comment or if you have found a solution please comment. Any help would be greatly appreciated