Lag, FPS and performance issues in Single Player Mode

My Computer is in good performance and has Java 64 Bit i have tried using the options menu in Minecraft for video settings but doesn't improve the frames per second at all. I also have tried other options by trying to improve my laptop and changing the ram memory of the game up higher but is still under 15 FPS. I tried re-installing Minecraft but made no change, i cant play my Minecraft at all because of the lag and low performance and getting to the point that i wont play Minecraft at all, My laptops fine its just the game itself, Minecraft is a brilliant game and enjoy playing it very day, please help fix this problem.

Thanks

Jake