Minecraft slowdowns - Help!

morkus64

Limp Gawd
Joined
Jan 22, 2006
Messages
143
Didn't have this problem before - minecraft slowing down every few minutes - basically goes to a crawl for maybe 30 seconds, then back to normal. I've uninstalled & reinstalled Java (32 and 64 bit) and minecraft. Played with settings (even on lowest it does this - again, this computer is more than capable of minecraft and used to handle it easily). No luck on all fronts.

Any ideas?
 

jmilcher

[H]ardness Supreme
Joined
Feb 3, 2008
Messages
4,465
Didn't have this problem before - minecraft slowing down every few minutes - basically goes to a crawl for maybe 30 seconds, then back to normal. I've uninstalled & reinstalled Java (32 and 64 bit) and minecraft. Played with settings (even on lowest it does this - again, this computer is more than capable of minecraft and used to handle it easily). No luck on all fronts.

Any ideas?
Computer specs? Minecraft version?
 

morkus64

Limp Gawd
Joined
Jan 22, 2006
Messages
143
Smasung RF510 (Core i7 Q720, 4GB ram, GT330M).

Minecraft 1.51 also did it on 1.47
 

H-street

[H]ardness Supreme
Joined
Feb 25, 2005
Messages
4,538
what is your memory usage?
play with F3 open and watch the memory usage.. i've had problems with minecraft sometimes eating up the memory over time.
 

morkus64

Limp Gawd
Joined
Jan 22, 2006
Messages
143
During the latest slowdown (a little more few and far between since I uninstalled 32 bit java), the used memory keeps climbing from 23% to 28%, then drops to 15% says of 910MB (why isn't it using all 4GB?)
 

morkus64

Limp Gawd
Joined
Jan 22, 2006
Messages
143
Nope, nevermind - still as common. Just takes a little while from the start for the first one. Then they come every minute or two.
 

aviphysics

[H]Lite
Joined
Sep 27, 2011
Messages
75
I ran into this problem after the 1.5 update.

The problem is that MineCraft isn't multi-threaded. You can fix this by using the OptiFine mod. It easily doubled my frame rate. My system is running a Q6600 at 3 Ghz and it was bogging down my single threaded performance. It is intermittent because the chunk loading is intermittent and uses a lot of CPU.
 

GushpinBob

2[H]4U
Joined
Dec 11, 2007
Messages
2,721
Do these slowdowns happen in every world you create or are they limited to a specific one? Maybe something that is causing a bunch of chunk updates e.g. redstone clocks, mob/animal farms involving water?

Maybe the problem lies outside of Minecraft. Have you checked in the Task Manager or Resource Monitor for anything suspicious or any other processes (outside of javaw, if minecraft is running) that are cyclically hogging CPU time or disk access?

Also, what power profile are you running in? Have you tried running under "High Performance"?
 

morkus64

Limp Gawd
Joined
Jan 22, 2006
Messages
143
Enabled multi chunk loading. Better, but still slows down. Can you recommend settings to use?
 

aviphysics

[H]Lite
Joined
Sep 27, 2011
Messages
75
Enabled multi chunk loading. Better, but still slows down. Can you recommend settings to use?
I can't give you specific recommendation because I am not running on a system with a low end GPU like you are, but this advice might help.

Each setting has a description of what the choices do to performance. I would start by adjusting all of them for max performance. Then turn up the settings you care about one by one and see what you can do while monitoring with Fraps. On my system, view distance has the biggest impact on performance but also is the most debilitating at low settings. It not only reduces GPU utilization but also greatly reduce CPU load. For me, multi-chunk loading fixed the cpu bottleneck problem.

I also recommend running with the window off to the side and monitoring GPU utilization with GPUz to see if your GPU is maxed out or not. Even better if you can connect a second monitor to view GPUz and run MC maximized.

For advanced OpenGL you are going to have to try the different settings and see what they do to performance. I got the best results on a Radeon 6870 with the Advanced OpenGL off, but AMD is terrible at OpenGL.
 
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wonderfield

[H]ardness Supreme
Joined
Dec 11, 2011
Messages
7,396
During the latest slowdown (a little more few and far between since I uninstalled 32 bit java), the used memory keeps climbing from 23% to 28%, then drops to 15% says of 910MB (why isn't it using all 4GB?)
That's typical of garbage-collected languages like Java. The memory usage will exhibit a 'sawtooth' pattern of allocation and deallocation.
 
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