I wanted to post a possible solution to this bug and wanted the developers to see this. When Minecraft is lagging on a good computer (or not) it may be because of java. Control Panel->search for java->go to java tab in popup->view->there will probably be more than one line of code that i assume causes Minecraft to use two different versions of java? When all Java installs are uninstalled and java 6_37 is installed only, Minecraft Runs great. Unknown if it runs well on version 7. When people see a new java update they download and install without uninstalling their previous java version, therefore causing this Minecraft Problem. Maybe Minecraft can be coded to only use the latest java version installed? I hope this information reaches the developers and i hope they make this info more public. Good Luck!
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I've updated my java to the latest possible, tried optifine, updated lwjgl and still my ticket got marked as invalid! The lag is intensifying with each update and there is nothing I can do about it except put up with it. Now so far almost every ticket about lag was ignored or marked invalid. You just have to experience it yourself to know what we all mean.
What are your computer specs (RAM / free memory (storage) / RAM you let minecraft use (other details))
tips to remove lag:
1. No texture pack
2. View bobbing - off
3. Particles - minimal
4. Graphics - fast (i think)
Generally speaking, it is not a requirement to uninstall previous versions of java before installing new ones, as an application can only run one version at a time (this should be the newest one installed). One cannot code into a java application the version it should run. If you want to try to reduce lag spikes, it is highly recommended that you update your java to the latest version. You can also try the optifine mod.