15/02/24 02:58:15.62 6b18nAno.net
いつぞやを境に「ローカル」に限ってマップの読込が一切できなくなってしまいました。
具体的な症状としては、マップロード中「Downloading terrain」の文字が出ている状態で必ずフリーズを起こしてしまいます。
その間、javaw.exeはCPUを20%前後占有、メモリ使用量は800MB前後を推移しています。
MOD全抜き、バージョンダウン、savesフォルダクリア（からのNew World作成）など試しても変わりません。
元々利用していたMODもOptiFineとShadersMod、あとSEUS程度になります。
マルチは何の問題も無くプレイできるのが謎で、完全に手詰まりです。
何方かご助力頂けませんでしょうか。
以下、Launcerから引っ張ってきたシステム情報と、起動→フリーズ→強制終了後に出るログです（余計なとこマスクしてたらすみません）
バニラ1.8.3で試したログになります。
[02:20:50 INFO]: System.getProperty('os.name') == 'Windows 7'
[02:20:50 INFO]: System.getProperty('os.version') == '6.1'
[02:20:50 INFO]: System.getProperty('os.arch') == 'x86'
[02:20:50 INFO]: System.getProperty('java.version') == '1.8.0_31'
[02:20:50 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'
[02:20:50 INFO]: System.getProperty('sun.arch.data.model') == '32'
[02:53:59] [Client thread/INFO]: Setting user: xxxxxxxx
[02:53:59] [Client thread/INFO]: (Session ID is token:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)
[02:54:01] [Client thread/INFO]: LWJGL Version: 2.9.4
[02:54:01] [Client thread/INFO]: Reloading ResourceManager: Default
[02:54:03] [Sound Library Loader/INFO]: Starting up SoundSystem...
[02:54:03] [Thread-6/INFO]: Initializing LWJGL OpenAL
[02:54:03] [Thread-6/INFO]: (The LWJGL binding of OpenAL. For more information, see URLﾘﾝｸ(www.lwjgl.org))
[02:54:03] [Thread-6/INFO]: OpenAL initialized.
[02:54:03] [Sound Library Loader/INFO]: Sound engine started
[02:54:04] [Client thread/INFO]: Created: 512x512 textures-atlas
[02:54:07] [Server thread/INFO]: Starting integrated minecraft server version 1.8.3
[02:54:07] [Server thread/INFO]: Generating keypair
[02:54:08] [Server thread/INFO]: Preparing start region for level 0
[02:54:09] [Server thread/INFO]: Preparing spawn area: 10%
[02:54:10] [Server thread/INFO]: Preparing spawn area: 15%
[02:54:11] [Server thread/INFO]: Preparing spawn area: 22%
[02:54:12] [Server thread/INFO]: Preparing spawn area: 28%
[02:54:13] [Server thread/INFO]: Preparing spawn area: 35%
[02:54:14] [Server thread/INFO]: Preparing spawn area: 43%
[02:54:15] [Server thread/INFO]: Preparing spawn area: 51%
[02:54:16] [Server thread/INFO]: Preparing spawn area: 58%
[02:54:17] [Server thread/INFO]: Preparing spawn area: 66%
[02:54:18] [Server thread/INFO]: Preparing spawn area: 73%
[02:54:19] [Server thread/INFO]: Preparing spawn area: 80%
[02:54:20] [Server thread/INFO]: Preparing spawn area: 88%
[02:54:21] [Server thread/INFO]: Preparing spawn area: 95%
[02:54:22] [Server thread/INFO]: Changing view distance to 32, from 10
[02:54:22] [Server thread/INFO]: xxxxxxxx[local:E:5cdfd8f2] logged in with entity id 286 at (-57.5, 87.0, 253.5)
[02:54:22] [Server thread/INFO]: xxxxxxxx joined the game
[02:54:54] [Client thread/INFO]: Stopping!