Updated java: [21:22:05 INFO]: System.getProperty('java.version') == '1.7.0_51'. Same problem continues. Crashed manually version 14w03b in opened superflat world and attaching that.
That was a complete log, I don't have to load any world for the problems to start. Attaching another one (development_console2.txt) that contains also opening a superflat world, exiting it and going back to create world -menu.
Attached also development_console.txt
Not sure if this is related to MC-45154, but I'm experiencing lag spikes every 5 sec (from 30 to 0/1 fps), and also the menus are really slow, especially world options menu.
I'm experiencing this too, and it's easily visible from world options menu when hovering mouse over buttons and waiting until they turn blue. This started with 14w02c, 14w02b and earlier versions work fine. I was trying to record the situation with bandicam, but when it's recording minecraft, the problem disappears. The same thing happens every time in the menu, and also with the newer snapshots. The game itself is also unplayable because lag spikes happen every 5 second or so (I guess that's the same issue?).
Video from create new world -> more world options filmed using camera: http://www.youtube.com/audio?v=L6qe_q5mJ9w
From the video you can also see that the first time it takes ~20 sec for the screen to react, the next time it's almost a minute.
There is nothing visible in developer log, and javaw process does not consume any CPU at this time and used memory amount is also stable.
I guess this is the same problem, block update seems to fix the situation: http://www.youtube.com/watch?v=XUOV6Jf0inY
This happens also in bigger areas, at least with cows. I created a 2 high sandstone wall with 4x8 area inside, and over 50% of cows died pretty much immediately after growing up.
Something else is wrong with the collision boxes even if the cows survive this. Rest of the cows that were originally small cows (spawned with eggs, but problem occurs also with the ones born "naturally"), died quite rapidly to suffocation when walking around the wall holding a wheat.
That fixed the problem for me, including the in-game lag spikes. Thank you.