I was working on my adventure map, testing out with the scoreboard. When I was done, I walked a couple blocks, making the all blocks disappear. I checked my F3 mode to see if I had teleported, as there were many random pressure plates near my location. It said that I was at the same location though, and slowly falling, as if in a chunk error, or a cobweb. As this was happening, my fps was reaching slow numbers, once at 120, now at 30. As it was happening, my memory was getting packed, with it quickly going from 30% to 90% in a matter of seconds. As I reached 0 on the y- level, My game crashed, with this report:

---- Minecraft Crash Report ----
// Why is it breaking

Time: 10/5/13 5:18 PM
Description: Exception in server tick loop

java.lang.OutOfMemoryError: Java heap space
at java.lang.StringCoding.set(Unknown Source)
at java.lang.StringCoding.decode(Unknown Source)
at java.lang.String.<init>(Unknown Source)
at java.util.jar.Attributes.read(Unknown Source)
at java.util.jar.Manifest.read(Unknown Source)
at java.util.jar.Manifest.<init>(Unknown Source)
at java.util.jar.JarFile.getManifestFromReference(Unknown Source)
at java.util.jar.JarFile.getInputStream(Unknown Source)
at sun.misc.URLClassPath$JarLoader$2.getInputStream(Unknown Source)
at sun.misc.Resource.cachedInputStream(Unknown Source)
at sun.misc.Resource.getByteBuffer(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at km.c(SourceFile:80)
at kl.<init>(SourceFile:28)
at kk.a(SourceFile:209)
at kk.d(SourceFile:343)
at jh.d(SourceFile:217)
at kv.a(SourceFile:274)
at gs.a(SourceFile:136)
at eb.b(SourceFile:63)
at kv.e(SourceFile:69)
at ky.b(SourceFile:40)
at box.b(SourceFile:83)
at net.minecraft.server.MinecraftServer.u(SourceFile:494)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– System Details –
Details:
Minecraft Version: 13w39b
Operating System: Windows 8 (x86) version 6.2
Java Version: 1.7.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 9865648 bytes (9 MB) / 518979584 bytes (494 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 634201 (35515256 bytes; 33 MB) allocated, 634201 (35515256 bytes; 33 MB) used
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 102
Profiler Position: N/A (disabled)
Vec3 Pool Size: 633 (35448 bytes; 0 MB) allocated, 633 (35448 bytes; 0 MB) used
Player Count: 1 / 8; [kq['creepervsdog'/274, l='F3AR official 0.0.1', x=6597.95, y=0.02461, z=302956.79]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

It only happens on this world, and no matter what I do, the bug duplicates.