Project Ozone 3 Server lag


New Member
Nov 27, 2019
First off:
  • I'm Running windows 10
  • Using my computer to host minecraft server
  • Project Ozone version: PO3-3.1.45Aserver
  • FTB Version:
  • I have added Vanillafix and Chunk-pregenerator to help with performance, along with other mods
  • Server specs are:
- cpu: AMD ryzen 5 1600x
- RAM: 32 gb RAM corsair vengeance
- Samsung SSD 970 EVO plus running on NVME M.2
- i benchmarked ssd with Samsung magician and it says it has 3282 MB/s Read and 3244 MB/s Write

So i wanted to make a server where me and my 2-3 friends could play together. I have a server running on the same computer that i am playing Minecraft.
I am experiencing lag in the forms of rubber banding, and "Cant keep up!" when just standing still/loading chunks (moving and exploring new dimensions etc.) Our overworld is skyblock and even then the server displays "Cant keep up! running 7742 ticks behind!"
I have been reading alot on forums and chats and basically done everything - from downloading mods that can help with performance to giving the server more ram.
I stumbled upon a reddit thread that was talking about JDK server istead of regular java so i siwtched to that - saw a little bit of performance boost but not much

server is currently running with these arguments on a bat file:

Echo off

java -server -Xincgc -Xmx25G -Xms25G -XX:NewRatio=2 -XX:CMSFullGCsBeforeCompaction=1 -XX:SoftRefLRUPolicyMSPerMB=2048 -XX:+CMSParallelRemarkEnabled -XX:+UseParNewGC -XX:+DisableExplicitGC -Xnoclassgc -XX:+UseFastAccessorMethods -XX:CMSInitiatingOccupancyFraction=90 -XX:+UseConcMarkSweepGC -XX:UseSSE=4 -XX:+UseCMSCompactAtFullCollection -XX:parallelGCThreads=2 -XX:+AggressiveOpts -XX:+UseLargePages -XX:ReservedCodeCacheSize=1G -cp ftbserver.jar -jar ftbserver.jar nogui
echo Type R to restart or Q to quit.
choice /c rq /n /t 10 /d R
if %errorlevel%==1 echo Restarting server... &goto :start

The last arguments are for easy efficient server restart instead of closing and re-opening the cmd. UwU

I have also switched to JDK as i mentioned.
( i downloaded OpenJDK 8 (LTS) OpenJ9 version)
I also have played around with and changed view-distance from 20 to 10
My internet speed is also good, i am running fiber optics so my speedtest is:

508 Mbps download
332 Mbps upload

Still i got a bunch of lag and rubberbanding on the server...
I have lately been trying pregenerating chunks - which is basically a way to load chunks before the player has to play on the server for example.
this makes playing on new dimensions and exploring less laggy because the chunks are already loaded...
I used chunk pregenerator from curse
I figured it would help so i just put it on for a few nights to load all the dimensions we were playing. But i still experienced some lag and "Cant keep up" messages... and thats driving me crazy...

We have been on the server for a while and made a few contraptions and machines - so it might be that but i am not sure...
I figured since i have almost 30 gb allocated to the server and that i have preloaded chunks aswell as run the server with parameters then it will work smoothly..
Is there anything that im missing?
Does anyone have any tips to what i can add/remove/change to the server as a whole to make it run smoother?

If you want any more info i am more than happy to provide them!

EDIT: I tried switching back to normal java and had a bit of more stable server, but the lag is still occuring...


Global moderator
Team Member
Global Moderator
Trusted User
Aug 29, 2014
First off, this is not a FTB pack - but with that said:

1 - lower view-distance to 8 in
2 - allocating 25gb out of 32gb in total on the same machine that you're running your client from is not something I wouldn't recommend, for 2-3 players, lower that to 6gb and check the memory demand, and give 1-2gb more at the time - don't go more than 12-16 for this, that should not be needed (unless crazy amount of loaded chunks with lots of stuff - just find the root cause first).

How much have you allocated to your client?
(make sure that isn't too much either, that will also cause lag for you 4-6gb should be enough for the client)

3 - Switching back to "normal" java - that's a good thing - keep using that.

Start with making these changes, and check how your server and client acts - don't over allocate ram, try to find the cause instead. Check out the mod Tickprofiler (only needed server side), and / or LagGoggles

If you have issues moving forward, reach out to the mod pack developer:
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