^ This. Also, Laokerry nailed the steps perfectly. I have done this a dozen times on my old G3 and it works well every single time, especially when the UI starts getting sluggish. Just a few things to keep in mind from a technical side before you pull the trigger:

• It will 100% erase everything on the internal storage. Your photos, contacts, and save games will be gone unless they are synced or moved.
• Pop your SanDisk Ultra 64GB microSDXC out before you start just to be extra safe, tho it usually only wipes internal memory.
• If you have a Google account logged in, make sure you know the password. Googles security lock (FRP) will kick in after the reset and you will be stuck at the setup screen otherwise. Honestly, doing a fresh start makes the phone feel way faster. If you are still having issues after the reset, it might be a battery thing, but usually, this clears up any software weirdness. Good luck!

To hard reset your LG G3, you can use either the menu option or a button combination. Here’s how:

Factory Reset via Menu

1. Open Settings.
2. Tap on Backup & reset.
3. Select Factory data reset.
4. Tap Reset phone and then Erase everything.

Hard Reset via Buttons

1. Power off the device and wait 10 seconds.
2. Press and hold the Volume Down and Power buttons.
3. When the LG logo appears, release both buttons, then immediately press and hold them again.
4. Release when the Factory data reset screen appears, and select Yes using the volume keys.

Note: A hard reset will erase all data on your device, so ensure you back up any important information beforehand.