League client running extremely slow randomly.

So I've been playing LOL for a while and I've never come across a time where my client suddenly stops running as well as it used to. So when i launched my client, it took about 20 seconds to let my type in my password and press Sign In. Once i got past all of that and hit Sign In, it would look like this: http://i.imgur.com/7mlo2yt.png) for about an hour or two, making me very bored and tempted to quit playing, and when it would, it would take time for the overview to even load, giving me multiple messages saying to check my internet and if its ok, then wait a few minutes to try again, which would never happen and lags my entire computer not letting me perform any action without a 2 minute delay in the game and in the background while i try and use a browser. I don't even attempt at trying to play or join a game as i know i would just be given a timeout because of how slow it is. It's hell to even close the application so i have to open task manager, which already takes a couple of minutes to even get there, to close it forcefully. I've looked up answers to this problem and I've found people with similar problems with the client from even months and years ago. Which would also mean I've tried the answers given to those people, which would not affect anything and I even tried to uninstall and reinstall, which did nothing but to add on, i can no longer play as i have to wait for the game to update so i could actually play and I spent about 3 or 4 hours with it being only 20%~ updated causing me to close it to write this meaning i will have to wait a whole day afterwards. I really enjoy the game but its unbelievable that this would randomly happen and destroy my LOL client, i found a hextech repair tool which didn't do anything and i'm very close to uninstalling the game and giving up on it as a whole. Please tell me a way to fix this problem.