Server Can't keep up! Is the Server overloaded

Got Big Problems with a Server Running on 20w09a. If 6 Players are Online everyone get Blockbugs and Mobs are bugging too.

Server got 32GB Ram and 16 Cores

Running Linux Ubuntu 18.04.4 LTS

Launchparameters are:

screen java -Xms26G -Xmx30G -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:MaxGCPauseMillis=50 -XX:+DisableExplicitGC -XX:TargetSurvivorRatio=90 -XX:G1NewSizePercent=50 -XX:G1MaxNewSizePercent=80 -XX:G1MixedGCLiveThresholdPercent=35 -XX:+AlwaysPreTouch -XX:+ParallelRefProcEnabled -jar server.jar