when i enter in a world/server the game freezes after abaut 10 sec

there is some problem for open the launcher but the biggest problem is
when i enter in a sever/singleplayer world the game freeze after abaut 10 seconds.....(minecraft premium)
i realized that when i push play The green bar does not charge completely and goes back.....and when i open a survival world there is only the script building terrain for ever, and isn't possible close the windows