A small, simple mod that allows to limit max chunk generation per tick for improved server performance.
The mod has 2 config options, both modifiable from GUI ingame:
chunksPerTick = 2
maxChunkGenMillis = 5
Vanilla defaults are 50 chunks per tick, and 50 milliseconds max. Minecraft by itself never reaches 50 chunks per tick generation speed within 50 ms, so the time is always exceeded. Chunk generation also causes several other parts of world tick to take more time, so it's not uncommon to see tick time in excess of 100ms.
With a lot of mods that significantly slow down world generation, even 1 chunk per tick may be too much, in that case there is no solution.