It seems that nobody is giving the OP a serious answer that relates exactly to what he is asking.
The things that cause FTB to lag.
- High Server population. Since this game has many features that require constant map updates in different parts of the world, more people using these features that do these changes cause lag.
- Mobspawners (especially Soul Shard Mod) create alot of entities, Soul Spawners at Tier 4/5 create entities, even when no-one is online. They have their own chunk loader.
- Spot/Chunk Loaders also create lag, each one of these loaders add 1 player population per chunk loader active.
- Liquids in Waterproof pipes and flowing liquids (especially in quarries)
- BC Pipes require tick by tick block updates when being used or not used, same with Conduits, liquiducts, AE Cables, and energy cables. Every tick, the game checks to see if there is anything is currently linked, to where it is being checked 20 times per second.
- BC Pipe and waterproof Pipe entities. Each entity again requires block updates and sometimes even severe frame drops when not picked up.
- Quarries, Mining Wells, Pumps, Mining Lasers, block breakers, Range weapons - All these machines require block updates within the chunks/blocks they are used. These require block updates ot check for block impact or to remove a block
- Player chunk loading - More chunks loaded by the player, accounts to more chunks actually being loaded.
- World Save - The more players/chunk loaders online, the more lag this will generate
- Logging Plugins - Block logging plugins for anti-griefing etc cause this lag, as it processes for every entity, block change on the map.
- Apiaries/Alvearies - do Block checks every tick to see whether or not there are flowers(and appropiate flower) or have access to sky and appropiate biome for the bee. It checks for bee, checks for data on that bee, compares each data to each block, biome in it's vicinity.
Now all these things, and many more cause small lag, but more of these amount to more lag. The following are not recommended for server play:
- Soul Shard Mod
- Ender Chests/Tanks
- Railcraft Mod
- Steve's Carts Mod
- Mining lasers, Block breakers
- Forestry Mod
- Buildcraft Mod
- Applied Energistics Mod
- RedPower2 Mod
- Thaumcraft 3 Mod
I don't recommend in disabling all these mods but disabling a few should greatly improve server stability in higher populations. Particular abusive mods like Soul Shard Spawners and Quarries (Larger than 1 Chunk) which are the biggest culprits in lag.
One thing to add: Dedicated Servers.
Most dedicated server hosts use the same package for Vanilla Minecraft for Modded Servers.
To run a very stable FTB Server, the Dedicated server requires the following:
- 10Mbps Upload, 100Mbps Download.
- +16GB RAM
- 300 Mbps transfer to HDD with Speed at 10k RPM
- FTB requires Multi-Thread ability or a very powerful single Processor. Minecraft doesn't support multi-thread.
To get these resources for a dedicated server, you're looking to pay about +$300 per month.
