once I've gone onto my world it will start slow then it will freeze then go onto crash report

/Users/summermercer/Documents/Minecraft Crash Report.docx

Minecraft Crash Report ----
// Ouch. That hurt 😞

Time: 23/09/15 12:52 PM
Description: Registering texture

java.lang.OutOfMemoryError: Java heap space
at bml.a(SourceFile:281)
at bml.a(SourceFile:271)
at bml.a(SourceFile:205)
at bme.a(SourceFile:47)
at bmj.a(SourceFile:56)
at bmj.a(SourceFile:38)
at ayu.a(SourceFile:621)
at ayl.a(SourceFile:80)
at ayw.a(SourceFile:36)
at ayu.a(SourceFile:558)
at bfk.a(SourceFile:1039)
at ave.av(SourceFile:915)
at ave.a(SourceFile:325)
at net.minecraft.client.main.Main.main(SourceFile:124)

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

– Head –
Stacktrace:
at bml.a(SourceFile:281)
at bml.a(SourceFile:271)
at bml.a(SourceFile:205)
at bme.a(SourceFile:47)

– Resource location being registered –
Details:
Resource location: minecraft:textures/gui/container/creative_inventory/tabs.png
Texture object class: bme
Stacktrace:
at bmj.a(SourceFile:56)
at bmj.a(SourceFile:38)
at ayu.a(SourceFile:621)
at ayl.a(SourceFile:80)
at ayw.a(SourceFile:36)
at ayu.a(SourceFile:558)

– Screen render details –
Details:
Screen name: ayu
Mouse location: Scaled: (211, 130). Absolute: (634, 410)
Screen size: Scaled: (427, 267). Absolute: (1280, 800). Scale factor of 3

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bew['prodrummer1'/77, l='MpServer', x=-142.62, y=209.00, z=-167.70]]
Chunk stats: MultiplayerChunkCache: 2209, 2209
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: 0.00,4.00,0.00 - World: (0,4,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 2898868 game time, 694 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 52 total; [wa['Skeleton'/0, l='MpServer', x=-181.59, y=237.00, z=-184.94], tp['Horse'/1, l='MpServer', x=-188.13, y=237.00, z=-114.69], vn['Creeper'/513, l='MpServer', x=-174.75, y=237.00, z=-224.09], vn['Creeper'/514, l='MpServer', x=-173.97, y=237.00, z=-217.50], vn['Creeper'/386, l='MpServer', x=-198.94, y=237.00, z=-159.66], wa['Skeleton'/515, l='MpServer', x=-185.19, y=237.00, z=-216.25], wa['Skeleton'/387, l='MpServer', x=-212.47, y=237.00, z=-165.88], tp['Horse'/3, l='MpServer', x=-184.97, y=237.00, z=-90.25], wa['Skeleton'/388, l='MpServer', x=-208.41, y=237.00, z=-120.88], wc['Spider'/389, l='MpServer', x=-212.13, y=237.00, z=-119.91], tp['Horse'/390, l='MpServer', x=-210.94, y=237.00, z=-112.97], uz['item.item.arrow'/5129, l='MpServer', x=-128.53, y=237.00, z=-184.94], wa['Skeleton'/10, l='MpServer', x=-174.94, y=237.00, z=-137.56], uz['item.item.bone'/5130, l='MpServer', x=-129.47, y=237.00, z=-184.81], vn['Creeper'/11, l='MpServer', x=-161.59, y=237.00, z=-120.25], tp['Horse'/12, l='MpServer', x=-166.38, y=237.00, z=-92.84], vo['Enderman'/17, l='MpServer', x=-150.16, y=237.00, z=-178.34], wc['Spider'/657, l='MpServer', x=-95.50, y=237.00, z=-224.50], vn['Creeper'/23, l='MpServer', x=-113.19, y=237.00, z=-164.22], tp['Horse'/24, l='MpServer', x=-122.09, y=237.00, z=-150.31], vn['Creeper'/25, l='MpServer', x=-124.50, y=237.00, z=-127.50], wc['Spider'/28, l='MpServer', x=-120.81, y=237.00, z=-109.28], wa['Skeleton'/545, l='MpServer', x=-156.22, y=237.00, z=-248.22], vn['Creeper'/546, l='MpServer', x=-144.50, y=237.00, z=-193.50], we['Zombie'/36, l='MpServer', x=-111.88, y=237.00, z=-176.28], wc['Spider'/421, l='MpServer', x=-203.53, y=237.00, z=-226.09], wc['Spider'/422, l='MpServer', x=-208.16, y=237.00, z=-195.69], wa['Skeleton'/423, l='MpServer', x=-210.31, y=237.00, z=-189.78], vo['Enderman'/424, l='MpServer', x=-218.38, y=237.00, z=-191.78], tp['Horse'/425, l='MpServer', x=-205.91, y=237.00, z=-173.28], wa['Skeleton'/426, l='MpServer', x=-211.28, y=237.00, z=-164.75], tp['Horse'/427, l='MpServer', x=-198.28, y=237.00, z=-100.56], tp['Horse'/428, l='MpServer', x=-194.06, y=237.00, z=-96.06], vn['Creeper'/684, l='MpServer', x=-70.50, y=237.00, z=-219.50], we['Zombie'/429, l='MpServer', x=-206.31, y=237.00, z=-110.84], we['Zombie'/685, l='MpServer', x=-74.56, y=237.00, z=-208.94], tp['Horse'/430, l='MpServer', x=-192.13, y=237.00, z=-96.63], uz['item.item.arrow'/3889, l='MpServer', x=-104.13, y=237.00, z=-158.72], uz['item.item.bone'/3890, l='MpServer', x=-105.06, y=237.00, z=-160.09], we['Zombie'/568, l='MpServer', x=-142.16, y=237.00, z=-218.31], uz['item.item.arrow'/3398, l='MpServer', x=-106.41, y=237.00, z=-112.56], uz['item.item.bone'/3400, l='MpServer', x=-105.50, y=237.00, z=-112.47], uz['item.item.bone'/4680, l='MpServer', x=-188.88, y=237.00, z=-115.69], we['Zombie'/591, l='MpServer', x=-126.66, y=237.00, z=-197.66], uz['item.item.rottenFlesh'/3537, l='MpServer', x=-98.09, y=237.00, z=-165.50], bew['prodrummer1'/77, l='MpServer', x=-142.62, y=209.00, z=-167.70], uz['item.item.arrow'/4696, l='MpServer', x=-122.94, y=237.00, z=-108.16], uz['item.item.bone'/4698, l='MpServer', x=-121.59, y=237.00, z=-107.44], uz['item.item.arrow'/3162, l='MpServer', x=-82.31, y=237.00, z=-191.50], uz['item.item.bone'/3163, l='MpServer', x=-82.81, y=237.00, z=-191.13], uo['entity.ItemFrame.name'/624, l='MpServer', x=-97.50, y=239.50, z=-256.03], uz['item.item.rottenFlesh'/3704, l='MpServer', x=-84.41, y=237.00, z=-146.34]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bdb.a(SourceFile:309)
at ave.b(SourceFile:2311)
at ave.a(SourceFile:334)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 1.8.8
Operating System: Mac OS X (x86_64) version 10.9.5
Java Version: 1.8.0_60, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 3351072 bytes (3 MB) / 1060372480 bytes (1011 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 5 total; -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.8.8
LWJGL: 2.9.2
OpenGL: Intel HD Graphics 4000 OpenGL Engine GL version 2.1 INTEL-8.28.36, Intel Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 4x Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz

Duplicate of MC-12949 – If you have not, please use the search function in the future, to see if your bug has already been submitted.
For technical support, please use the Mojang Support Center.

--- This action was performed automagically. If you believe this was done erroneously, please :light_bulb_on: raise an issue.

How much ram your
mac has? if it has low amount
then that means Minecraft is not
getting enough allocated ram.
I'm not a tech guy but that could
be the reason. Also go to
Mojang support for technical
support, not the bug tracker.