Group texting with Iphone users, my texts get delayed until theirs all stop
Even I own a galaxy s4 and I know that the latest update has been so terrible. I don't think that Samsung is anyway going to push any updates for this but follow the solution below.


You can wipe the cache partition from the recovery mode. (Shut down and reopen by pressing menu, power and volume button at once) then scroll down using volume button to wipe cache partition and power button to confirm. Reboot the device.
Very important go to developer options and switch off all the animations.


Follow some more from. http://www.androidpit.com/galaxy-s4-lollipop-problems-and-how-to-fix-them