DimensionalThreading VS lazydfu

The Dimensional Threading mod offers this on 1.16+ fabric servers

You don't need to redesign the server. You can just use these mods.

Dimthreads may cause some issues, though seemingly none that are similar to yours https://github.com/WearBlackAllDay/DimensionalThreading/issues. Also make sure you configured it to use more than 3 threads since you have additional dimension mods (Aether);

Starlight performs substantially better than phosphor and greatly speeds up terrain generation. Krypton for networking performance. C2ME or tic-tacs (both aim to do the same thing and are not mutually compatible) greatly improve world loading and terrain generation but are experimental and, in my experience, not compatible with a lot of other mods. Dimensional Threading puts each dimension on a separate thread, but also tends to not be very compatible with other mods. FerriteCore aims to reduce ram usage. This page has a whole list of mods.

(Experimental) Dimensional Threading ( WearBlackAllDay/DimensionalThreading )

SOLVED: Thanks for the suggestion! I just figured out the problem. I had the experimental mod called Dimensional Threading installed on the server https://github.com/WearBlackAllDay/DimensionalThreading.

From LazyDFU's github repo:

1) LazyDFU: Compiled DFU rules afterwards. 2) EntityCulling: Doesn't render entities that you can't see 3) NoFade: This isn't exactly a performance mod, but fading sometimes makes my game crash, so I use this. 4) NotEnoughCrashes: Again, not a performance mod, but makes crashes much easier to handle. 5) SmoothBoot: Makes Minecraft not hog too many resources when starting up 6) SodiumExtra: Basically adds more options to Sodium. 7) Hydrogen: idk how to describe this (I no longer don't use this as 1.18 hasn't released yet, but I'll this in anyway). 8) C2ME: Improves chunk performance. 9) Enchanced Block Entities: Improves rendering of block entities. Note that this only really shows effect when you're in an area with tons block entities (eg. your storage basement)

LazyDFu v0.1.2

I would suggest you to use Sodium or Iris - Overall Performance Improvement / Iris If You Wanna Use Shaders Too Lithium - Improve CPU Usage LazyDFU - Launch Game Faster Phosphor - Improve Light Engine Hydrogen - Reduce Memory Usage

I'd recommend checking out some of the mods in the fabulously optimized modpack. Most notably I'd recommend LazyDFU, No Fade, and Smooth Boot as they're most applicable to the problem you're describing.

(Experimental) Lazydfu ( astei/lazydfu )

You could try installing Hydrogen and LazyDFU t see if they do anything for this. Hydrogen will reduce Minecraft's Memory usage, which should help with the GC pauses slightly. LazyDFU will improve startup times and reduce the massive amount of garbage from DataFixerUpper during startup (Mojang's backwards compatibility system), which might also improve things during gameplay as well.