[Client] - No friends list, client slows down after an hour of being open.

Hey, so i've had a couple issues with the client that have been intensifying over a couple weeks now, with my folders in my friends list not showing the correct people in them (I have a couple friend folders for real life friends/duo partners, and the such, which have been showing people in them that i've never put there.), and they have finally culminated into the ultimate issue. I no longer have a friends list. All of my folders and friends have disappeared from my client, and they don't even show up in my message tab. Not only have I been having friends list issues, but if I leave the client open for about an hour, it slows down to the point where it takes 30+ seconds to get into the end-game lobby, 10+ seconds to press the "Play Again" button, and 10+ seconds to press the "Start Queue" button, not to mention that its almost impossible to choose a champion in champ select.

The link is a screenshot of my league client with no friends list.