Did you do a factory reset after the update? I would highly recommend doing this if you have not. As has been mentioned in numerous other posts, its always good to do a factory reset after a major update, if you experience these types of issues after, whereas you didn't have them before. There are MANY factors in play when updating with a major update. Prior to reset, go into recovery mode and select the option to wipe cache...this will NOT delete your important data. If the problem still exists, then a factory reset would be recommended, hope this helps!
Turn off the phone and remove the battery, then reinsert
Press and hold the Volume Up key and Home key, then press and hold the Power key
When it vibrates release the Power key
The recovery menu should appear - release the other keys
Navigate using the Volume keys to Wipe all cache (power key to select)
Press the Power key to reboot