Because of my stupidity, I left my phone charing at night and some how fell asleep and left open a flash light application, so basically my flash was on for hours and hours and my phone couldn't die because it had a charger plugged in so it kept going, and just to put the cherry on top, I fell asleep on top of my damn phone! This caused my GS4 to get extremely hot and I woke up for school and realized that this could be bad, my battery especially was very hot and I removed it from the phone and a little later I put it back on and charged the phone. What I noticed was my phones battery drained throughout the school day and I was not happy about this because I was quite frankly enjoying the longevity of my battery life! So now I suffer bad battery life despite using battery savers! What's also as bad is that my phones performance got worse! It studders and lags much more than usual, and the gaming performance is also now laggy! This is so horrible because I was truly enjoying this phone so much it was so amazing until the incident so I was wondering if I replace the battery for a fresh new one will my phone be back to normal in battery life and performance wise? I keep wondering (sorry if I'm ignorant about this!) if the battery life and especially the phones performance is based upon the battery? Is it based on the battery or the internal phone??? Please help and thanks for reading!