Over time, I've come across a plethora of posts online discussing various ways to enhance performance in modded Minecraft. I've experimented with many of these suggestions with differing results, so I decided to compile all the tips and tricks into a single comprehensive guide.

Note: While I’ve labeled this as the “ultimate guide,” it's important to understand that some systems may simply be unable to run certain modpacks. To give you an idea, I'm currently running FTB Revelations with 5 GB of allocated RAM at approximately 100 fps without issues using the following specs:

• Intel Core i7 3630QM @ 2.40GHz
• 8.00GB Dual-Channel DDR3
• NVIDIA GeForce GTX 670MX
• 698GB HITACHI HDD (no SSD)

If your PC's specifications are on par with or better than these, you should also be able to run similarly demanding modpacks effectively. Now, let’s dive into the guide.

Identifying the Problem

Performance issues are typically caused by either RAM or GPU limitations. To determine the source of your problems, start your preferred modpack and open the Task Manager to monitor resource usage.

If your GPU appears to be underutilized, it’s likely not the issue. If it shows minimal usage, you might be using a laptop and relying on integrated graphics (often Intel Integrated Graphics). To resolve this, follow these steps for NVIDIA users:

1. Open the “NVIDIA Control Panel.”
2. Navigate to “Manage 3D settings.”
3. Click on “Program settings” and add each instance of “javaw.exe” on your PC (usually found in both Program Files and Program Files(x86)).
4. Set them to use the “High-performance NVIDIA processor.”
5. Rename your launcher (Twitch Launcher, MultiMC, etc.) to “minecraft.exe.”

This should ensure Minecraft utilizes your dedicated graphics card. If you have an AMD GPU, the procedure should be similar, though I can't provide exact steps.

If your GPU is running close to 100% usage, continue with the guide for further troubleshooting.

Next, check your RAM usage. For an 8 GB system, I recommend allocating no more than 6 GB to Minecraft, ideally around 4 or 5 GB. If you have 12 or 16 GB of RAM, you can safely allocate 8 GB but should not exceed that. If your RAM is nearing 100% usage, delve deeper into the guide. If not, then RAM isn't likely the culprit.

Addressing GPU Usage Issues

Before proceeding, it’s worth noting that your graphics card might not be powerful enough for modded Minecraft. However, if your specs are similar or better than those listed above, you should manage.

To minimize GPU usage, begin by closing any other applications that might consume GPU resources. Check your Task Manager and close any problematic programs. Then, look for your Minecraft instance (generally a Java app) in Task Manager, right-click it, select "Details," and set its priority to "High."

Additionally, there are mods available that can lessen GPU load, which you’ll discover in the "Mods to Add & Remove" section of this guide.

Tackling RAM Usage Problems

For a lot of players, the primary issue stems from RAM, as Minecraft isn't usually overly demanding on the GPU. A great first step is to close any applications consuming significant RAM, like Chrome or Discord. Beyond that, I’ve encountered two effective methods.

Method One: JVM Arguments

Many of you may already be familiar with this method. I’m not an expert here, so I’ll point you to a Reddit post that offers detailed history, reasoning, and a comprehensive tutorial. Note that in MultiMC, the "-Xmx4G -Xms4G" arguments can’t be set via JVM arguments, so you'll need to manually allocate RAM (5 GB for an 8 GB system, or 8 GB for those with 12+). Other posts recommend different JVM arguments, but this is currently the most popular one I’ve seen.

Personally, I didn't experience substantial performance gains with this method, but many have found it beneficial, so it's worth a try.

Method Two: Changing the Virtual Machine

This method involves switching the Java Virtual Machine from Hotspot (the default) to OpenJ9. Again, I recommend a Reddit post that explains the entire process clearly.

I found this adjustment to be a game-changer. It drastically reduced my lag spikes from several seconds down to smooth performance. I highly recommend giving this a try.

Mods to Add & Remove

This final section covers mods that can enhance your game performance, regardless of whether the underlying issue is RAM or GPU-related. I suggest using some of these mods even if you aren’t currently experiencing performance issues.

First, consider the classic singleplayer vs. multiplayer discussion. Playing on a server means your PC mainly handles the client side, which can improve performance, but it limits your control over mod installations. If you love Kitchen Sink or Quest Book packs, multiplayer is ideal. For custom or less popular packs, singleplayer may be better. However, if you can host a server on a separate machine, that offers the best of both worlds.

Client-Side Mods:
I recommend installing the following four mods for every modpack, regardless of your situation:

• BetterFPS
• TexFix
• VanillaFix (also includes server fixes; install it client-side and server-side)
• FoamFix (commonly included in most modern modpacks)
• Smooth Font (has marginal impact on performance but may help)
• OptiFine (divisive; may help, may cause crashes with certain mods)
• Phosphor (also server-compatible)

Server-Side Mods:
These are beneficial only if you’re playing singleplayer or running your own server:

• Ai Improvements (can technically be installed client-side but offers minimal performance boost)
• Born in a Barn
• Chunk-Pregenerator (helpful during world creation, can be uninstalled post-creation)
• Tick Dynamic (requires setup, boosts TPS)
• Stackie
• Surge (has client-side functions)
• Clumps (requires client-side installation)
• FastFurnace (increases TPS, needs client-side installation)
• FastWorkbench (similar to FastFurnace)
• Multithreaded Noise (requires client-side installation)
• Unloader

And that wraps up the guide. I hope you found something here that helped improve your performance issues. If there's anything I’ve overlooked, please feel free to let me know, and I’ll do my best to update it.