Why am I lagging?

1. Right click the Start button → Device Manager
2. Expand "Display adapters"
3. If you only see one entry like "Intel UHD Graphics" or "AMD Radeon Graphics," you don't have a dedicated GPU — none of this applies to you, your PC is doing the best it can already.
4. If you see two entries (one Intel/AMD integrated, one NVIDIA GeForce/RTX/GTX or AMD Radeon RX), you've got a dedicated GPU and the rest of this guide is for you.

If none of the below match what you've got, search your whole drive for "javaw.exe" in File Explorer and use whichever one is newest / matches your launcher's folder.

1. Open Settings → System → Display → Graphics (or search "Graphics settings" in the start menu)
2. Click "Browse" and add: javaw.exe (from above) and your launcher's main exe (CurseForge.exe, PrismLauncher.exe, ModrinthApp.exe, ATLauncher.exe, TLauncher.exe, minecraft.exe — whatever you use)
3. Click each one once added, hit Options, and set it to "High performance"

This is the important one — Windows Graphics Settings alone doesn't always get respected, especially on laptops.

1. Right click the desktop → NVIDIA Control Panel (if missing, your drivers are probably outdated — see Step 5 below)
2. Manage 3D Settings → Program Settings tab
3. Click "Add" and browse to the same exes from Step 1 (javaw.exe and your launcher exe)
4. For each one, set "Preferred graphics processor for this program" to "High-performance NVIDIA processor"
5. Apply

1. Open AMD Software (Adrenalin)
2. Go to the Gaming tab
3. Add the game/exe manually if it's not listed
4. Set Graphics Profile to "High Performance"
5. There's also a "Switchable Graphics" section under System → Display or in laptop-specific settings, depending on your version — check there too if Gaming tab doesn't have it.

There's usually no physical switch between the two GPUs (Optimus on Nvidia laptops, AMD Smart Shift/Switchable Graphics on AMD). The integrated GPU is always connected to the screen, so you'll always see some usage on it even when the game renders on the dedicated card — that part is normal. What's not normal is the dedicated GPU sitting near 0% the whole time you're in a loaded world.

Some laptops (MSI, Asus, Lenovo, etc) also have their own control center app (MSI Center, Armoury Crate, Lenovo Vantage) with a hybrid graphics / GPU mode setting buried in there — look for "Hybrid," "Optimus," "Discrete GPU only," or "MUX Switch."

Outdated or half-broken drivers can ignore every setting above. Grab the latest driver straight from the source rather than trusting Windows Update: NVIDIA — nvidia.com/drivers (or GeForce Experience / the NVIDIA app) · AMD — amd.com/support

Still having issues? A clean reinstall with DDU (Display Driver Uninstaller) run in Safe Mode, followed by a fresh driver install, fixes a surprising number of "my dedicated GPU won't kick in" problems caused by leftover driver conflicts.

Open Task Manager → Performance tab, click your dedicated GPU, and watch the usage while actually walking around in a loaded world (not just the loading screen). It should be doing the heavy lifting now, not your integrated graphics. You can also press F3 in game and check the bottom right corner — some versions show which GPU is rendering, though Task Manager is more reliable.

Restart your launcher completely after making any of these changes — half the time it doesn't take effect until you fully close and reopen it. A full PC restart fixes it if closing the launcher alone doesn't.

• Double check you actually edited the right javaw.exe — modpacks can have more than one Java install on the same PC and it's easy to set the wrong one.
• Try setting both the Windows Graphics setting and the NVIDIA/AMD control panel setting at the same time — don't rely on just one.
• Some prebuilt desktops have the monitor cable plugged into the motherboard instead of the dedicated GPU, which forces everything through integrated graphics no matter what software you set. Check which port your monitor cable is in and move it to the GPU's port if needed.

• -XX:+UseG1GC — turns on G1 ("Garbage First"), a collector designed to clean memory in small, regional chunks instead of pausing everything at once.
• -XX:+ParallelRefProcEnabled — lets G1 process references (the bookkeeping behind weak/soft references mods use a lot of) across multiple CPU threads instead of one, shortening pauses.
• -XX:MaxGCPauseMillis=200 — tells G1 to aim for pauses no longer than 200ms. It's a target, not a hard guarantee, but it steers G1's internal tuning toward short, frequent pauses instead of rare, long freezes.
• -XX:+UnlockExperimentalVMOptions — required flag that unlocks the experimental G1 tuning options used below (G1NewSizePercent, G1MixedGCCountTarget, etc).
• -XX:+DisableExplicitGC — ignores System.gc() calls some mods make manually. Manual GC calls force a full, expensive collection at a random time — this stops mods from triggering one over your head.

G1 splits memory into regions and these flags shape how it sizes and recycles them. Minecraft allocates and discards huge numbers of short-lived objects every tick (block updates, entity ticks, packets) — these settings keep the "young generation" big enough to absorb that churn without constantly triggering collections.

• -XX:G1NewSizePercent=30 / -XX:G1MaxNewSizePercent=40 — keeps 30-40% of the heap reserved as "young generation" space for those short-lived objects, instead of G1's much smaller default.
• -XX:G1HeapRegionSize=16M — sets a larger region size, better suited to a heap in the multi-GB range than G1's auto-picked default.
• -XX:G1ReservePercent=20 — keeps 20% of the heap held back as a safety buffer so G1 doesn't have to fall back to a slow full GC if it runs low on space.
• -XX:G1HeapWastePercent=5 / -XX:G1MixedGCCountTarget=4 / -XX:G1MixedGCLiveThresholdPercent=90 — control how aggressively G1 reclaims mostly-empty regions during "mixed" collections, spreading the work over more, smaller collections instead of one big one.
• -XX:InitiatingHeapOccupancyPercent=15 — starts a collection cycle earlier (at 15% heap usage instead of the default 45%), trading slightly more frequent small collections for avoiding sudden large ones.
• -XX:G1RSetUpdatingPauseTimePercent=5 — caps how much of each pause is spent on remembered-set bookkeeping, leaving more of the pause budget for actually freeing memory.

• -XX:SurvivorRatio=32 — shrinks the survivor space ratio, which suits Minecraft's mix of mostly very short-lived objects with a smaller set that sticks around.
• -XX:+PerfDisableSharedMem — stops the JVM writing performance-monitoring data to disk continuously, which removes a small but constant source of disk I/O (helps more on slower drives — see cause #7).
• -XX:MaxTenuringThreshold=1 — promotes surviving objects to old generation faster instead of copying them between survivor spaces repeatedly, which is cheaper for Minecraft's allocation pattern.

• -Dfml.readTimeout=90 / -Dfml.loginTimeout=90 — Forge/NeoForge (FML) properties that raise how long the client waits while exchanging mod/registry data with the server during login, from the short default to 90 seconds. A pack this size can take a while to sync on first join or after an update — without this, slower connections or PCs can get kicked with a "timed out" disconnect before they even finish loading in.

Copy the flags above with the button, then paste them into the JVM/Java Arguments field for this instance — append them after anything already there (like your -Xmx memory setting), don't delete what's already in the box.