I have had the same problem, there are some ways to speed up your PC, right click on my computer, go to properties, next go to advanced system settings, then the first settings button, then adjust for best performance, then apply; also, when your game is loaded, but while still at the screen for which saved world to play, press control, alt, and delete keys together, go to task manager, then processes, find javaw.exe right click and set priority to high. Change ram usage to 2gb, I was running it on 15, somehow it works better on 2, Finally I went to creative mode in the game, enchanted a diamond axe, and chopped as many big trees as I could before too much boredom set in!! (not sure if I needed to enchant the diamond axe or not, but I figured it was better to err on the side of caution! On youtube there are vids on how to do this stuff! I hope this is helpful!!