I have an odd habit. I pretend that both lwjgl or slick2d are some kind of optimization way. So I'm planning to complete project in java2d completely and port it to one of them. I feel it wrong but better

Well, you
do get hardware rendering, which should be a huge performance change. Heh, I also just use Slick2D for it's hardware rendering, and when I find myself wanting to use pathinding for instance, I think "That's wrong! Do it yourself, so you'll learn something!", so I always end up reimplementing a lot of it's features if I need them
