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I've recently uncovered a new lag spike of death and it kind of scares me. This lsod however is easily fixable and is relatively easy to predict. It happens when you reach 494/494MB used memory. This no longer causes your game to crash unless you have a weak GPU, but with strong GPUs causes multiple short lag spikes until you close minecraft and restart it. So far that is the only thing that will cause and fix this lsod. Hope this helped people, as if you play mc in the same window for a SUPER long time this will happen, and it is not prevetable... My PC (Which is a laptop but still has a strong GPU) only gives me lag spikes. My Windows XP which has a weak and old (Dinosaur 10 yrs achievement) GPU just causes it to crash mc altogether. Hope this helps, once again, and i will add a poll below to compare people's answers to this.

This belongs in the Disscussion section.

This is the java garbage collector doing a full GC because the memory allocated to the game is full. Increasing the memory to 1G should alleviate the lag spikes.

Well poopy microsoft did something fun

Does not belong here. Belongs in Discussion.

Like others said, this is in the wrong section.

However, I've never had problems with this myself while playing normally, even with 32 bit Java/OS and 512 MB (slightly less in F3) allocated, even after playing for 6 hours straight (note - in fullscreen, although that shouldn't make a difference, but the game does run better for me in fullscreen, especially in complex areas; other people may see lower performance). Of course, this is in 1.6.4, and 1.8 does have issues with extreme memory allocation rates, but even there it shouldn't be a problem unless you try to use a high render distance (Optifine even lets me go up to 32 chunks without allocating the 2 GB Mojang requires in vanilla; of course, this makes the game crash with "OutOfMemoryError: Java heap space").

An exception, oddly enough, is when I make test worlds and create a Superflat world after making normal worlds, which seem to break Java's garbage collector, and/or not properly discard the objects used to generate normal worlds, as memory usage no longer rises and falls normally but remains near the limit with only a small drop on full garbage collections, which is likely indicative of a memory leak in the game; this is pretty reproducible and doesn't happen when making several normal worlds in a row (setting off a ton of TNT can also cause a memory leak in older versions).

Also, I seriously doubt having a good GPU will prevent you from crashing, as this has nothing to do with the GPU, which has its own dedicated VRAM; most likely, you are running out of system memory or process space due to the older computer having a 32 bit OS/Java version (note that if you open Task Manager it will show javaw.exe as using far more memory than reported in-game and on 32 bit systems processes are limited to 2 GB of total process space, including the Java heap (Minecraft), OpenGL (including texture memory), and Java itself). Ironically, reducing memory allocation can actually help in some cases, as noted here. (as usual, the moderators seem clueless, just telling you to allocate more memory, with a much of replies saying that it didn't help).

On the other hand, my computer does have some extremely bizzare "lag spike of death"-like issue running any version after 1.6.4; it doesn't seem to be a hardware performance issue since it sometimes go away if I leave the game running unfocused (oddly enough) and when it happens it always happens on a fixed interval of 10 frames, with an underlying "wave" pattern of FPS variability, as I showed here (note the good FPS otherwise, aside from lag spikes in biomes like jungles, and chunk loading in 1.8, which Optifine can reduce/eliminate but this issue is still a big problem; switching to full screen will also cause it to come back so I can't just let the game sit until it clears up, then go to fullscreen to play normally). It is also completely unaffected by any settings (GPU, JVM arguments, memory allocated, and so on; even artificially reducing FPS, including running another program to cause lag by stealing CPU time, keeps the spikes at the same number of rendered frames, and no, this has nothing to do with "prerendered frames" in the GPU control panel, which Optifine's creator suggested to me as the problem).

Hover your mouse into auto save. The desc says that the two seconds are not recommended. Causes a famous Lag Spike Of Death!

Please increase the delay of auto save. Maybe it helps

If this doesn't help, memory might be slow, change the memory size to four gigabyte.
http://rs1291.pbsrc.com/albums/b549/Yazanalhabal/Mobile Uploads/IMG_20150114_084255_zpse091d34e.jpg~320x480

You should get 64 bit java, if you have a 64 bit system. That's how I fixed my lag problem. You could also try to fix your lag a little bit by turning down some settings.

Quote from Yazan_Al_Habal»

If this doesn't help, memory might be slow, change the memory size to four gigabyte.

Uh, you have no idea how memory works... memory speed is completely different from memory size... the only way to fix "slow" memory is to upgrade your computer. Also, Optifine's creator themselves said that allocating more RAM is NOT a solution, unless you are running on extreme render distances or using inefficient mods (I say inefficient because my own mod doesn't increase memory usage) or HD texture packs; even in 1.8 the game runs fine with only 512 MB of memory allocated; really:

So regardless and conclusion what bit version of the JVM, memory allocation is not an issue here. A fault belies elsewhere between 32 bit and 64 bit. However it is not memory nor machine specific. It could be GPU display driver level, or if want to say LWJGL itself. So yes there is a performance issue when running Minecraft on a 32 bit java environment, but as to true cause, it certainly is not memory related.

it very well could be LWJGL as 1.7 + uses a newer version and that is when my bizarre "lag spike of death" problem started; this also has nothing to do with autosave since the frequency is always the same, every 10th rendered frame, with an underlying up/down wave at the same rate (i.e. not just spikes); autosave also likely only does anything on pre-1.3 versions, due to the internal server separating game logic from rendering; indeed, I do get lag spikes from autosave on very old versions but not on newer versions, with 1.3+ performing much better in general, no doubt due to the client/server splitting the load over two CPU cores, even as they do introduce some overhead. Similarly, Optifine's claim that it "doubles FPS" became invalid (in my experience) when Advanced OpenGL was added to vanilla - yes, that is where Optifine's original "doubles FPS" claim came from as it originally added it, and indeed, it does double my FPS when enabled.