Performance Problems on high-end server and client

So, im setting up an Server with around 10-20 players and 290 Mods on Forge 1.20.1. I already included a lot of performance-mods and also c2me and pregenerated a lot of chunks. The server runs great so far, but I experience severe framedrops in a certain time period on the client and sometimes the server spits out an "PlayerXY moved too fast". I think its called rubberband-effect. If I press F3+ALT in my client, it looks really good and green, but sometimes (like around every 15-30s) i get one or two single red collumns in the graph and i feel a stutter.

Im not sure how I should handle that properly. SyncChunkWrites is on false and i set the network compression treshold to 384. The max chained neighbors are set to 1500 due a lot of tech-mods. Im using Java 21.

So far im not certain if I should use ZGenerational/ZGC in general, because I am not sure about the latency. I'm neither a java programmer nor a network engineer. I tried diffrent JVM-Args and they all gave a similar result, the sawtooth in the Server-Window was really big and it took around 30s for the garbage collector to do its job. The Ram usage always fell from 13GB to 4GB.

Also I'm not aware about the NUMA-situation. As far as I know it should be used on an Epyc, but I found no sources saying anything clear about my scenario with minecraft.

The server is my own and located in my house, its nothing from a hosting service or anything.

System:

• Epyc 8224P (6 threads used for the minecraft server vm)

• 128GB DDR5-RDIMM (24GB allocated to the minecraft vm, 22GB allocated to the game)

• Server OS: Debian 12 Bookworm (LXDE)

• MC-VM-OS: Debian 13 Trixie (LXQT)

• JAVA: Adoptium Temurin 21 OR Oracle GraalVM 21

Client: Ryzen 9 5900X, 32GB DDR4-3000, 3070Ti Vision. (16GB allocated to the game), Java 21 GraalVM

Spark Profile:

https://spark.lucko.me/Jf7YTq4aBf