Since Forge asks me to report this :)

21:55:17	game		info	[20:55:17] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-28, 9 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.
21:55:18	game		info	[20:55:18] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-30, 16 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.
21:55:18	game		info	[20:55:18] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-30, 14 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.
21:55:19	game		info	[20:55:19] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-27, 2 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.
21:55:20	game		info	[20:55:20] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-29, 3 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.
21:55:20	game		info	[20:55:20] [Server thread/WARN] [FML]: Geolosys loaded a new chunk (-30, 1 Dimension: 0) during chunk population, causing cascading worldgen lag. Please report this to the mod's issue tracker. This log can be disabled in the Forge config.

Duplicate of #18, won’t fix - sorry. Disable the forge error pop up in the forge config if it bothers you.