EDIT: I was saying "However" too much.
My computer is an OK piece of hardware. When I first downloaded Minecraft, I got a steady FPS rate of around 35-50 FPS (which is pretty good for a laptop). However, when playing in 1.7, my framerate drops to around an average of 20. Also, occasionally when the sun sets or rain begins, it causes a huge lag spike that lowers me down to 9 FPS max. This occurs much more frequently during extended periods of play. Next, after about a half hour, I run into an FPS barrier. My framerate drops to around 3-5 FPS and occasionally freezes, and it takes about 10 minutes to recover and go back up, whether I continue playing, exit Minecraft, or shut off my computer. Also, when it does go back up, my framerate hovers around 10-13 FPS and only exiting MC for ~5 minutes will bring it back up. I never had these problems in 1.6 or 1.5.