Heavy Lag/ Crashes

I recently updated Minecraft today and within 5 minutes I realized when items were dropped or moved they jittered through the air, the frame drops also occurred when looking about, or moving about. I have never experienced frame drops before the update and the last time I played was yesterday and I haven't changed anything. 

The crashes occurred when I Alt+Tab out the game and back into it, it freezes on the screen and you try to Alt+Tab back to something else but it stays and it's there until you Alt+F4 out the game or use the window key and hover over the icons 'x' and close it. This doesn't happen all the time but it is very frequent.