I've been doing some research on causes of server lag with FTB/Mindcrack servers.
Large machine constructions with lots of entities being transported in pipes.
- Players need to minimize pipes and tubes AND limit how many items are in said pipe at a time. For example if your base has a few hundred separate items (a stack is treated as one item) in pipes this uses the same cpu load as that many creepers.
Solar Ultimate Hybrid Solar Panels placed but not connected.
- simple this one connect it up or put it in a chest. Soaryn had one on the forgecraft server causing 32 log entries a second ( most likely was just a glitch but caution pays off)
Uncontrolled mob grinders ie those that aren't turned off with a redstone signal.
- build/move your mob grinders to chunks that are normally unloaded. In normal FTB the solution would be tier5 soulshard grinders only that require a preasure plate to activate and no automatic farming grinders.
Mo'creatures' conflicts with vanilla and other with custom spawning mods doesn't help with this either as it causes more mobs to spawn in chunks and at times due to it's maximum spawn number no creatures in other areas.
Pyro on the Mindcrack server was causing block lag because his iron golem farm had 1700 golems in it.
Poorly placed ic2 eu cabling. Grid patterns are bad . (including copper and glass fibre)
-Players really need to paint wiring and create proper circuits. IC2 and by default Gregtech use a requesting system to send EU to machines. Each machine requests EU and this is sent via the cable to the supply/batt box. With multiple paths for a request to travel the cpu usage is increased exponentially at each fork/intersection. Grids are bad.
Thaumcraft nodes and flux when mismanaged.
-Always practice safe Thaumcraft, do not build towers at the largest node you can find as nodes refill from node larger than themselves and natural crystal deposits.
Silver wood trees CAUSE flux when planted.
Merging nodes causes flux and lowers total vis in an area, merging nodes where the largest node is less than 125 will reduce the size of the combined node instead of increase.
Hopefully when we are updated we will have the Thaumic bees addon which have bees who eat flux.
Insufficient power to IC2/Gregtech machines.
- Power your machines with the correct packet size and total EU. A machine that requires 128eu/t can be supplied on a LV(32eu/t) circuit as long as it it getting 4x32eu packets per tick. When we see server announcements about a machine grumbling the server log file is being spammed which can cause excessive ram and cpu usage.
Multiple dimensions (worlds)
- We have this under control as players can't make them.
- Are the current dimensions being used enough to justify the extra ram and cpu usage? i personally would like to eventually have buildings on all the dimensions including the end
The above is just my opinions based on some research. The admins would be able list more server specific problems and solutions i'm sure.