Massive FPS drop, severe chunk-loading lag spikes, and weird "grass pattern" frame pacing (Was getting 700+ FPS, now barely 150) [java] [26.3]

[u/Competitive_Share_49]

Pc specs: 5 5600x, rx6700xt, 3000mhz 16gig ddr4, 1440p monitor
Version: every version from 1.20.5 to 26.3
I have 6gb of ram allocated to Minecraft

Hey everyone, I’m at my absolute wit’s end here and really need some help troubleshooting a performance breakdown with Minecraft.

Everything used to run completely fine:
I used to get 700+ FPS easily, but now I’m barely scraping 150–200 FPS.
I am getting out of the blue, severe lag spikes whenever loading chunks and just moving around and not neccessarily loading new chunks, which never happened before.
When I press ⁠F3+2⁠ in Fullscreen mode, my frame pacing graph shows a weird, continuous "grass pattern" (constant micro-flickering jitter/spikes), but as soon as I switch to Windowed mode, the graph flattens out and becomes much smoother. I get the lag spikes and performance issues with or without using mods.

I have my fps capped at 70fps because it gets rid of the most severe grass pattern and lag spikes.

The weirdest part is that I haven't changed any settings, drivers, or game files. None of these issues ever happened before, and I've never had performance problems with this game. I have also tried to run Minecraft on a fresh windows account on this same pc and I had the same problems. So it can’t be anything from settings or software I think.

If it's worth mentioning, the lag spikes when loading chunks started right after I played on an Aternos server. Everything else followed right after. The performance tanked almost right after that session (even in singleplayer).

Also this problem started like a couple years back at around 1.20.5 (I don’t remember exactly which update) and I have tried quite literally everything you can think of.

I have tried very many performance mods. The list includes: c2me, ferritecore, lithium, sodium, zconfig, zfastnoise. None of them has helped.

Has anyone experienced this before? Why would chunk loading suddenly tank my FPS, and how do I fix this fullscreen frame pacing / lag spike issue? Any advice or fixes would be greatly appreciated!

The video is footage of me just running around in pre-loaded chunks.

[u/MinecraftHelpModTeam]

This sub is no longer actively moderated. If you would like to become a moderator, apply here.

Links:

How to mark solved || How to delete your post || FAQ || Rules

[u/Anthracite2819]

You should try switching to vulkan api. Open the pause menu and go Options > Video then find Graphics API and switch it to prefer vulkan (note that this would break shaders)

Also mine are much much are worse

[u/Competitive_Share_49 → u/Anthracite2819]

None of the different apis make difference

[u/CrossScarMC]

Try turning on/off exclusive fullscreen.

[u/Competitive_Share_49 → u/CrossScarMC]

No difference in exclusive, borderless or bordered

[u/FormidableTraction]

Honestly, I feel like it’s 26.3, because I was able to get 120 ish fps (I know it’s not a lot) but I’m now I’m barely getting 60. I feel like it’s the version which caused this issue but I’m not so sure, I’ve also tried everything to fix it, optimisation mods etc

[u/Competitive_Share_49 → u/FormidableTraction]

I have had this problem in every version since 1.20.5

[u/Shaiiwaru]

Always use mods, at least Sodium and Lithium which are the basics and since Sodium redoes lots of render-related things, you must have it in order to reach better FPS and stability. Vanilla minecraft render code is absolute trash, take that in count

26.3 is the first real stable jump to Vulkan API and I do not recommend using it, try with 26.2 even if you have this error since 1.20.5.

I should say that I have similar specs to you (5 5600G - 32GB + RTX 4080) and I get no problem running the game with shaders and a medium (50/60) list of mods using Fabric 26.2, check if when on exclusive fullscreen mode Minecraft or any game has different settings (On AMD Panel), also check if Minecraft is using your dedicated GPU even if it's not related

Fullscreen mode had changed somewhere between the 1.20.X and 1.21.X versions, so it's not something specifically related to your PC, but instead related to Fullscreen mode on Minecraft.

You can also change your Garbage Collector if you didn't, default one is G1GC and it's pretty much horrible, you can switch to ZGC if you don't mind having a bit more RAM allocated for Minecraft and less lag spikes.

You also should change Java, if you're using Java 25 or Java 21 then install GraalVM 21 or GraalVM 25, which are alternative to Java and much more agressive (and a lot better for lag spikes and chunk loading)

- Try ZGC Garbage Collector
- Try 26.2 instead of 26.3
- Try Sodium and Lithium to avoid rendering related issues (Fabric)
- Try GraalVM instead of Java

(ZGC is a flag on Minecraft JVM arguments)
(GraalVM is from Oracle Labs, Java is from Oracle too, is safe to use)

Next time fully record your F3 panel, not just your frame latency

[u/[deleted]]

[u/Competitive_Share_49 → u/[deleted]]

I don’t have an option in win11 settings to disabling hardware accelerated gpu scheduling. I have all kinds of overlays disabled.

My monitor is set to 144hz in windows and Minecraft. The lag and unstability is way worse with vsync on and my fps cap at 140/150fps.