If you’ve ever been deep in a cave, mid-swing against a Creeper, and suddenly your screen freezes for a split second, you know the pain. That’s the "stutter." It’s usually not your graphics card's fault. Honestly, it’s probably just Minecraft starving for memory. The game defaults to a measly 2GB of RAM, which is basically nothing if you’re running modern versions like 1.20 or 1.21. Even worse? If you’re playing a modpack like SkyFactory or All the Mods, 2GB won't even get you past the loading screen.
Learning how to allow more RAM for Minecraft is the single most effective way to kill those lag spikes. It’s not just about making the game run "faster"—it’s about giving Java the breathing room it needs to handle world generation and entity tracking. But here’s the thing: you can actually give it too much RAM. Java uses something called Garbage Collection (GC). If you give it 16GB of RAM for a vanilla world, the GC gets lazy, lets the trash pile up, and then freezes your game for five seconds while it finally cleans up. It's a balancing act.
The Quick Fix: Using the Default Minecraft Launcher
Most people use the standard launcher, so let’s start there. It’s buried under a few menus, which is probably why most players never find it. You don't need to be a coder, but you do need to know where to find your "JVM Arguments."
First, open the launcher and click on the "Installations" tab at the top. Find the version you’re currently playing—usually "Latest Release"—and click the three little dots on the right to hit "Edit." You’ll see a button that says "More Options." Click that.
At the very bottom, there’s a text box labeled JVM Arguments. It’s filled with a bunch of scary-looking code. Look for the very first part: -Xmx2G. That 2G stands for 2 gigabytes. That is the ceiling. If you want to allow 4GB, change it to -Xmx4G. If you’re on a heavy modpack and have 16GB of total RAM in your PC, you might change it to -Xmx8G. Save it. Done.
Why 4GB is Usually the Sweet Spot
You might be tempted to just slide that number up to 12 or 16. Don't. Unless you are running 300+ mods or a massive 512x resolution texture pack, 4GB to 6GB is the "Goldilocks" zone for Minecraft.
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Minecraft is an old game. Its engine, while heavily updated, still relies heavily on a single CPU core for many tasks. Throwing 32GB of RAM at it won't fix a slow processor. In fact, excessive RAM allocation leads to "stuttering" because the Java Virtual Machine (JVM) has to scan all that memory to find what's still in use. Smaller heaps are easier to clean. Stick to 4GB for vanilla and 8GB for big mods.
What About Third-Party Launchers?
If you use CurseForge, Prism, or Lunar Client, the process is actually way easier. These launchers know that players need to tweak memory, so they put the slider front and center.
CurseForge and Prism
In CurseForge, you don't even have to edit individual profiles. Go to the "Settings" (the gear icon at the bottom left), click on "Minecraft" under the Game Specific section, and scroll down. There's a "Java Settings" slider. Just drag it to where you want it. Prism Launcher is similar; you can set a global memory limit in the main settings or right-click an instance to override it for that specific modpack.
Lunar and Badlion
For the PvP crowd using Lunar Client, it's right in the main launcher settings before you even hit "Launch." It usually gives you a suggested range based on your hardware. Listen to those suggestions. They’ve optimized their clients to work within those bounds.
Common Mistakes: The "Out of Memory" Error
Even after you allow more RAM for Minecraft, you might still crash. "Out of Memory" doesn't always mean you didn't give it enough. Sometimes it means your computer literally doesn't have it to give.
If you have 8GB of total RAM in your laptop and you tell Minecraft to take 6GB, your Windows OS (which needs about 2-3GB just to exist) is going to start fighting the game. When your OS runs out of physical RAM, it starts using "Pagefile" memory—basically using your hard drive as RAM. Hard drives are thousands of times slower than actual RAM. This is when your game turns into a slideshow. Always leave at least 2GB or 3GB for your operating system and background apps like Discord or Chrome.
Java Versions Matter More Than You Think
In 2026, we’re mostly past the days of manually installing Java 8, but it still trips people up. Modern Minecraft (1.17 and up) requires Java 17 or 18. If you are trying to allocate more RAM but using an outdated 32-bit version of Java, you will be capped at about 1.5GB regardless of what you type in the JVM arguments.
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The official Minecraft launcher handles this for you by using its own "bundled" Java runtime. However, if you're using a custom launcher or a server, make sure you're pointed at a 64-bit JDK. You can check this by typing java -version in your command prompt. If it doesn't say "64-Bit," you're going to have a bad time.
Beyond RAM: Optimizing Performance
RAM is the floor, not the ceiling. Once you've allocated enough, you should look at mods that actually manage how that memory is used.
- Sodium / Rubidium: These are the gold standard. They rewrite how Minecraft renders chunks, often doubling or tripling FPS.
- FerriteCore: This is a literal "memory usage" mod. It reduces the memory footprint of Minecraft by several hundred megabytes by optimizing how models are stored in RAM.
- LazyDFU: (For older versions) This stops the game from loading unnecessary data right at start-up, making your game open faster.
Checking Your Work
To see if your changes actually worked, hop into a world and press F3. Look at the top right corner. It will show "Mem:" followed by a percentage and some numbers like 2048MB / 4096MB. If that second number matches what you typed into your launcher, congratulations. You’ve successfully opened the floodgates.
Actionable Next Steps
- Audit your hardware: Press
Ctrl + Shift + Escto see how much total RAM you actually have before you start changing settings. - The 50% Rule: Never allocate more than 50% of your total system RAM to Minecraft if you want to keep your system stable.
- Update your drivers: Specifically your GPU drivers (Nvidia/AMD), as they often dictate how efficiently the allocated RAM is used for textures.
- Test in increments: Start at 4GB. If it still lags, try 6GB. Don't just jump to 12GB immediately.
- Use the right flags: If you’re tech-savvy, look into "Aikar’s Flags." These are specific JVM arguments designed for Minecraft servers that work wonders for high-RAM clients to prevent those "Garbage Collection" stutters.
Adjusting your memory settings isn't a magic wand, but it's the foundation of a smooth experience. If you're still seeing lag after giving the game 6GB and installing Sodium, it might be time to look at your CPU's single-core clock speed or your storage drive's read/write limits. But for 90% of players, that little -Xmx tweak is all it takes to go from a stuttering mess to a silky-smooth adventure.