I have an LG G2 as well and it is extremely slow! I don't have a lot of pictures or apps either and often clear my running apps in case that has anything to do with it. It is terrible. Even slow when I type the letters come up after ive typed them and im on to another word.
I've tried to clear the cache and that still does not help. Also, the original charger that came with the phone is not working as it should. I keep getting the popup message about the charger not being compatible when it is the manufacturers charger that was in the packaging. Have you had that problem?