The mod appears to load chunk after chunk whilst world generation (the list goes on and on like so):
[22:50:57] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-13, 22] in dimension 0 (overworld) while populating chunk [-13, 23], causing cascading worldgen lag. [22:50:57] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-13, 21] in dimension 0 (overworld) while populating chunk [-13, 23], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-12, 22] in dimension 0 (overworld) while populating chunk [-13, 23], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-11, 24] in dimension 0 (overworld) while populating chunk [-12, 22], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-10, 25] in dimension 0 (overworld) while populating chunk [-11, 24], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-10, 26] in dimension 0 (overworld) while populating chunk [-10, 25], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-10, 28] in dimension 0 (overworld) while populating chunk [-10, 26], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-9, 29] in dimension 0 (overworld) while populating chunk [-10, 28], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-9, 28] in dimension 0 (overworld) while populating chunk [-9, 29], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-8, 27] in dimension 0 (overworld) while populating chunk [-9, 28], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-7, 27] in dimension 0 (overworld) while populating chunk [-8, 27], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-5, 27] in dimension 0 (overworld) while populating chunk [-7, 27], causing cascading worldgen lag. [22:51:00] [Server thread/WARN] [FML]: Please report this to the mod's issue tracker. This log can be disabled in the Forge config. [22:51:00] [Server thread/WARN] [FML]: RandomTweaks loaded a new chunk [-3, 27] in dimension 0 (overworld) while populating chunk [-5, 27], causing cascading worldgen lag.

My config file: https://pastebin.com/ZkkkHShE
Should I force stop the server or wait?

Went over the config file again, the only things I changed are the ocean floor generation values

265 is probably much too high for clayVeinSize. Try a lower value and see if that works.