Garbage TPS on good Hardware

https://preview.redd.it/nn29e3n3mq1e1.png?width=339&format=png&auto=webp&s=46fb4b45bace4ff57e319aac9d334d592ce709c8

https://preview.redd.it/6h4skks6mq1e1.png?width=206&format=png&auto=webp&s=25796cccf3bbe28397ee6b1c90c74321400f1942

Hey, so I have the Problem I'm currently on a Server with my Friends and we are playing Vanilla+ type stuff. So a few datapacks and even less plugins. We are around 10 players max on a server and have 12G Ram and 4 Cores of a Ryzen 9 5950X. So the hardware is definetly not the issue. I pregenerated the overworld (forgot the nether and end but that shouldn't be the problem as no ones in the nether) and did most of the optimization stuff in the config. Still we have an average of 13TPS. Someone got an Idea what could be the problem? Using the newest paper build for 1.21.3