BAD PERFORMANCE IN PC AND INPUT DELAY

Well the error I've been experiencing is that when I'm in the menus, out of nowhere, the game drops to 10-15 fps, making it unplayable (this happens randomly in any scenario). Sometimes it happens in the menus, or I'm playing a match perfectly and when it gets to the first half, it drops to 10-15 fps, making it unplayable. Right now, it's also been happening to me when I enter a match and the response rate is absurdly high, making it impossible to play the match. The only way to fix it is to put the game in windowed mode, and this has happened to me in every match I've played. I think it's ridiculous that they release a game for over £60 and it's UNPLAYABLE, and that they release patch after patch and can't fix this error.