Server keeping one core at 100% while idle

[JordanG13]

When launching a server from the included serverpack in CurseForge, the server keeps one thread at 100%. Other mod packs do not do this, and normally the usage is about 20% or so for one core (while idle).

System Information

OS: Ubuntu Linux
Java: JDK 21 Temurin
Additional Arguments: Aikar's Flags

Expected Behaviour

While idle, the CPU usage for a single core is considerably lower.

Actual Behaviour

CPU usage for single core is at 100%.

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I'll try and debug while I can, and if I find a fix, will let you know here.

[JordanG13]

Looks like there is a bug in efn (EpicFight Nightfall):

net.minecraft.Util.handler$cjb000$efn$modifyTime() - 37%

is what is keeping the server running at high CPU while idle