When I open a world in the latest snapshot, I see this. I tried removing the java argument that allowed me to use 2GB RAM, but then it just crashed. Here is the log if it helps:

Completely ignored arguments: [--nativeLauncherVersion, 286]
[13:40:03] [Client thread/INFO]: Setting user: diamond_boots
[13:40:03] [Client thread/INFO]: (Session ID is token:925f9e38c14648098d4366bb31b0d2be:3c2eb616702c4b3d96dc117f22eab237)
[13:40:05] [Client thread/INFO]: LWJGL Version: 2.9.4
[13:40:05] [Client thread/INFO]: Reloading ResourceManager: Default
[13:40:05] [Sound Library Loader/INFO]: Starting up SoundSystem...
[13:40:05] [Thread-5/INFO]: Initializing LWJGL OpenAL
[13:40:05] [Thread-5/INFO]: (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[13:40:06] [Thread-5/INFO]: OpenAL initialized.
[13:40:06] [Sound Library Loader/INFO]: Sound engine started
[13:40:07] [Client thread/INFO]: Created: 1024x512 textures-atlas
[13:40:12] [Server thread/INFO]: Starting integrated minecraft server version 15w41b
[13:40:12] [Server thread/INFO]: Generating keypair
[13:40:12] [Server thread/INFO]: Preparing start region for level 0
[13:40:13] [Server thread/INFO]: Preparing spawn area: 82%
[13:40:14] [Server thread/INFO]: Changing view distance to 12, from 10
[13:40:14] [Server thread/INFO]: diamond_boots[local:E:3a32dbe1] logged in with entity id 276 at (-77.71456251546506, 74.0, 244.1687845886112)
[13:40:14] [Server thread/INFO]: diamond_boots joined the game
[13:40:15] [Server thread/INFO]: Saving and pausing game...
[13:40:15] [Server thread/INFO]: Saving chunks for level 'Messing Arround world'/Overworld
[13:40:15] [Server thread/INFO]: Saving chunks for level 'Messing Arround world'/Nether
[13:40:15] [Server thread/INFO]: Saving chunks for level 'Messing Arround world'/The End
[13:40:18] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2488ms behind, skipping 49 tick(s)
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1. A fatal error has been detected by the Java Runtime Environment:
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2. EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00007ffaaf644fdc, pid=1324, tid=2372
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3. JRE version: Java(TM) SE Runtime Environment (8.0_25-b18) (build 1.8.0_25-b18)
4. Java VM: Java HotSpot(TM) 64-Bit Server VM (25.25-b02 mixed mode windows-amd64 compressed oops)
5. Problematic frame:
6. C [ig75icd64.dll+0x524fdc]
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7. Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
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8. An error report file with more information is saved as:
9. C:\Users\Nicholas\AppData\Roaming\.minecraft\hs_err_pid1324.log
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10. If you would like to submit a bug report, please visit:
11. http://bugreport.sun.com/bugreport/crash.jsp
12. The crash happened outside the Java Virtual Machine in native code.
13. See problematic frame for where to report the bug.
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    AL lib: (EE) alc_cleanup: 1 device not closed
    Java HotSpot(TM) 64-Bit Server VM warning: Using incremental CMS is deprecated and will likely be removed in a future release