Select Low Fps chunks 1.15.2

There is 3 chunks with extremely low fps 14-18 fps compared to the regular 100 fps. I have loaded this file in vanilla and it has no fps drop. Only plugins are world edit and armor stand edit (tested server with out them, same fps drop). What might be causing this/How can I fix this?
More info: 1.Client and Server side are both running windows 10,
2.x64 bit.
3.Java version is 1.8.0_251
4.no wrappers
5.CraftBukkit version 1.15.2(CraftBukkit version git-bukkit-8160e29, I don't know where to find a newer version) on getbukkit.
6.
7.