Server performance is not very good with so many mods, and I have been looking into ways to fix this. One of the latest comments on the ATM8 page on CurseForge is from XZot1K, and says the following:

After lots of testing I resolved most of my issues by installing the following mods to the server (Ensure to install the correct versions, as of writing this the version is latest of each for 1.19.2):

https://www.curseforge.com/minecraft/mc-mods/too-fast

https://www.curseforge.com/minecraft/mc-mods/smooth-chunk-save

https://www.curseforge.com/minecraft/mc-mods/chunk-sending-forge-fabric

https://www.curseforge.com/minecraft/mc-mods/packet-size-doubler

These mods will resolve larger packet disconnect issues, chunk lag, and irregular movement rubber banding.

In addition to these, for further improvement, set the tick rate to -1 in the server.properties file.

Paste the following into the bottom of your "user_jvm_args.txt" (change the 6GB and 256m to your liking

Xms must be less than Xmx):

-Xmx6G -Xms256m -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=32M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -Dusing.aikars.flags=https://mcflags.emc.gs -Daikars.new.flags=true

Please note that while these additional mods do work on the client the major improvement comes from the server-side.

I've already used those jvm arguments, but I didn't look for performance mods before. Now, after fiddling a bit around with them, the server feels much snappier (and I don't have to install anything client side)! I'm hosting on Azure, with a Standard D2s v3 (2 vcpus, 8 GiB memory) VM, and when I would do a /home from a far away place it would take a few seconds to load. Now, it's almost instantaneous! Thanks XZot1K! :)

The server also used to crash whenever multiple people entered the Nether, but I haven't been able to test this yet with the new configuration.

If you have any tips to improve performance, please share them here :)