1. Enter the following based on your device model:
3845#*855# (for International model)
3845#*851# (for T-Mobile)
3845#*850# (fot AT&T)
5689#*990# - LG Hidden Service Menu Thanks to @ericdabbs SPRINT G3
Dial: ##228378 + send, LG Hidden Service Menu (Reduced) ... Thanks to @asialove2013 VERIZON G3
!!! Verizon- don't know,because when you enter model number of these two carriers nothing happens. Someone could check this out and tell me !!!
2. Scroll down to High Temperature Property OFF,and select
3. Turn it ON...
4. Turn G3 fully off...
5. Wait at least 10sec...
6. Turn it back on and wait about 30sec. when Screen Lock shows...
!!! NEW ADDON !!! For more speed... Tested by me for 14 days... Everything went excellent! Follow these steps after you have done those above...
1. Again enter hidden menu according to your device model number
2. Select Thermal Daemon Mitigation OFF
3. Turn it ON
4. Turn OFF your G3.
5. Wait for around 30sec
6. Turn it on and after lock screen appears unlock it
7. Wait for at least 60sec more for G3 to finish sync and stuff
8. BOOM much more fluid and much faster G3
... BUT... Now that you have activated Thermal DAE you display will not lower screen brightness anymore. So if you put it to 90% it will stay 90%,if you put it to 100% it will stay there (be caution at 100%,test it)... I put mine to 80-90%,and never had G3 hot or misbehave strangely while playing games,recording 4k video,shooting pictures... Just one thing I noticed... IT IS BLAZING FAST Also you can test it after Clean Master clean up like by Antutu and see test results.
And of course you can buy me a BEER,Heineken
"NOTE" I am not responsible for any damage made to your phone!
P.S This is the same problem as on G2