Minecraft Forums

and how do i prevent it?

The only thing I can recall that helped those who experienced that back then was Optifine:

http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/1272953-optifine-hd-c3-fps-boost-dynamic-lights-shaders

Do these lag spikes occur at a regular interval of 2-3 seconds apart? That's the infamous "lag spike of death" which is caused by broken autosaving and the fact that there was no internal server back then, so any lag in what is now handled by the server (including saving) affects FPS. Another cause of periodic lag spikes is insufficient memory allocated to the game but that is unlikely unless you've reduced it; even 512 MB should be more than enough for such old versions (many posts on the Optifine blog show only 256 MB allocated to Beta versions); you can tell if this is the issue since memory usage will rise to 100% before dropping down along with a lag spike.

In order to reduce the LSOD issue you need to install Optifine; you can find older versions here. However, Optifine is only available for Beta 1.4 and newer (it did not exist before then).

Note that installation is much more complex than just clicking on a jar file since there was no installer prior to release 1.6.4 (1.6.2 and older versions are zip files, later versions use executable jar files, which can still be installed manually); you have to manually add the files to the Minecraft jar (located in the versions folder of the .minecraft folder; the easiest way to find it is to click on "edit profile" in the launcher then "open game dir"), following most of the instructions listed here (I suggest using a real zip utility and not simply extracting the jar since this causes issues due to certain filenames in some versions), as well as editing the json file to remove a ink to the jar download so the launcher doesn't redownload it.

(Fun fact - I've decompiled Optifine (for 1.6.4) and the "autosave" button actually does nothing (the value it sets is not used); I presume that when the client-server merger occurred in 1.3 this was broken or became redundant; the internal server saves data about once a minute based on how often it updates level.dat; I've only seen the LSOD on Beta versions myself)

odd how this "lag spike of death" didnt seem to occur when those versions were new :/

Quote from jingm»

odd how this "lag spike of death" didnt seem to occur when those versions were new :/

and are you using the same OS and same version of Java as back then?
Stuff changes.

For that matter, are you using the same JVM parameters as back then? Number one cause of lag spikes is self inflicted due to increasing Xmn.