Sir Lumbo

Hello, I have been playing Tekkit Legends for last 2 months. Everything has been working fine until now. When I loaded up my world, the game crashed saying "Java has stopped working". At first I thought it was just a broken save, but it turns out that I cant play any saves, even the ones I have just created. So I decided to re-install Tekkit Legends. It seems like the game doesnt crash anymore, but theres a big problem. I usually have around 40 fps, but now I struggle to get 5, even in the main menu. I have re-installed again and again, but the problem is still there. Any ideas? Thanks in advance