Server TPS goes down as soon as someone new joins

This all starts as a normal friend server with no lag at all. However, when we started to include certain plugins, lag started to raise slowly but heavily. I was tasked with fixing this issue.

What I did was remove all the unnecessary plugins and fix some spawn rates within the mobs.

After I did all of that, everyone has a fine experience EXCEPT me. Whenever I join the game, the server starts lagging over and over, going from 20 tps to 6-7 TPS in just 30s-1m. I've already asked many of my friends playing, and they say "There's no lag at all."

That's all I can say for now.

Quote from AlexanderSniper1

Try this for reduce lag:

https://support.aternos.org/hc/en-us/articles/360027350792

And this to get a better performance and optimization:

https://www.spigotmc.org/threa…mization%E2%9A%A1.283181/

Even though it's actually a solution, it's quite ambiguous on how to actually fix it.

Those articles work in general situations, however this is not one of those. In fact, I've already tried those 2 weeks ago. Didn't work at all. About the second link about spigot, it's actually useful, however quite vague in terms on how to actually get better performance.

Anyhow, thank you for trying to help.

I also forgot to mention I was using Optifine 1.16.3 to play in the server. However I just changed to Vanilla minecraft version and it's still the same.

I'm actually using PaperMC right now as well too..

I actually think the problem might with the files to be honest, however I do not know how I can confirm this.

Currently using 1.16.3

And yes, I know about 1.12.2+ being unstable in terms of performance.

I'll also be giving an update later (prob 1 day or so) in terms of TPS, as it seems it has increased a bit after I changed back to Vanilla Minecraft Version.

Alright. I'm back from some testing. Basically lag has decreased, however there's still some.

Another question, what does deleting playerdata do? If so, which playerdata do I delete? (Talkin' bout old or new)