So i played RLCraft a while now, and i started to notice some lags, but my FPS counter always says that im ~130-144. so i turned on the lagometer, and there i noticed some lag-spikes, idk why but i was fine until it rly started to get aonnoying and unplayable so i searched for others with the same problem and i didnt found a solution that helped me out, so i tried more RAM, less RAM, lesser graphic, but it didnt work.
And i saw that the color on the lagometer is purple and that means someting with "Chunk Upload" but idk why the chunk upload is causing lag spikes and it also says something about ~600 or ~800 mb/s on the bottom left, but idk what it means...

this guy had the same kind of problem

side Info:
RAM: i gave this pack 6Gb RAM (out of 16)
CPU: AMD R7 2700X 4.2GHz
and i play without any shaders, texture pack etc.

Thx for help :d