Ive been on a galaxy note4 in lollipop and for months I've been seeing android freeze up and hang for about 3 to 10 seconds when a new message is being received. If I am typing in another application I tend to push the key over and over when it doesn't register on the screen so when the message finally comes in and the system stops being frozen I get a large buffer of keystrokes that get written out at once. And if it's the delete key I tend to lose at least half my message. VERY annoying. Seems to be some contention with the stock messaging. But my notifications have been disabled there. And I disabled tetras floating notification and that didn't seem to help either.