Quote Originally Posted by Project View Post
Ever since season 1 people have been having some lag issues in LoL.

One way to try and fix this would be that once you start a game in LoL alt tab out and close the LoL client (not the game) since this is what's taking up so much memory.

You will have to restart your client once your game is over.
^ Yup, that's probably the reason. It happens every now and then but usually gets fixed by restarting the client or restarting your computer.
To me it used to happen when I closed the game abruptly (Alt + F4), so I advice you don't do that.