I thought this might happend but when I loaded up a world with ocean level 255 it worked fine at 60fps at first. Then I loaded chunks and I guess the blocks updating underwater slowly crashed my game
This is my crash report:
---- Minecraft Crash Report ----
// Shall we play a game?

Time: 7/24/14 2:42 AM
Description: Tesselating block model

java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at csu.b(SourceFile:88)
at chc.a(SourceFile:156)
at cjs.a(SourceFile:254)
at cjs.b(SourceFile:105)
at cjs.a(SourceFile:45)
at cjs.a(SourceFile:35)
at cjq.a(SourceFile:62)
at cmt.b(SourceFile:156)
at cmm.a(SourceFile:71)
at cmm.run(SourceFile:31)
at java.lang.Thread.run(Unknown Source)

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

– Head –
Stacktrace:
at java.util.ArrayList.rangeCheck(Unknown Source)
at java.util.ArrayList.get(Unknown Source)
at csu.b(SourceFile:88)
at chc.a(SourceFile:156)
at cjs.a(SourceFile:254)
at cjs.b(SourceFile:105)

– Block model being tesselated –
Details:
Block: minecraft:dirt[snowy=false,variant=dirt]
Block location: World: (-32,64,-835), Chunk: (at 0,4,13 in -2,-53; contains blocks -32,0,-848 to -17,255,-833), Region: (-1,-2; contains chunks -32,-64 to -1,-33, blocks -512,0,-1024 to -1,255,-513)
Using AO: false
Stacktrace:
at cjs.a(SourceFile:45)
at cjs.a(SourceFile:35)

– Block being tesselated –
Details:
Block type: ID #3 (tile.dirt // atz)
Block data value: 0 / 0x0 / 0b0000
Block location: World: (-32,64,-835), Chunk: (at 0,4,13 in -2,-53; contains blocks -32,0,-848 to -17,255,-833), Region: (-1,-2; contains chunks -32,-64 to -1,-33, blocks -512,0,-1024 to -1,255,-513)
Stacktrace:
at cjq.a(SourceFile:62)
at cmt.b(SourceFile:156)