Hello All! Ever since 1.3.1 came out for bukkit, My server has been going out of control performancewise lately. I will provide as much information as possible to those who may need it and help me solve my issues with my server. Server Information: Dedicated 16 GB Server from OVH Kimsufi Intel(R) Core(TM) i5-2310 CPU @ 2.90GHz: The CPU usage for Java hangs around 150% , however server load is around 1.00-1.50, and rarely uses up all of one or more cores. 2TB HDD @ 7200 RPM, I can assure you that it is not an I/O issue, as iowait times are low, the java process is always in S or R state, never in D state, and the iotop shows no high I/O activity from the server process. Relevant Details: - Minecraft Version: 1.3.1 - Operating System: Linux (amd64) version 2.6.32-5-amd64 - Java Version: 1.7.0_05, Oracle Corporation - Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation - Memory: 1084331456 bytes (1034 MB) / 3542417408 bytes (3378 MB) up to 9544400896 bytes (9102 MB) - JVM Flags: 3 total; -Xmx10240M -XX:+UseParallelGC -XXarallelGCThreads=4 - Type: Dedicated Server Plugins/Bukkit-wise Information: Bukkit Version: git-Bukkit-1.3.1-R1.0-b2320jnks (MC: 1.3.1) Bukkit Plugin Profiling (/timings) : http://pastie.org/4547778 WorldGuard Report: http://pastie.org/4548033 Plugin List: http://pastie.org/4547997 Background and Issue Information: 1. The TPS drops below 5 within >~6 Hours of the server being Up. Before that the TPS is always around 15-20, with No Lag Spikes at all. 2. Ram Usage is super high, garbage collector is on in the java start command. At first, the server uses up only about 2-4 GB of Ram with ~75-100 Players on, then at the same time when the TPS drops, the RAM usage suddenly increases slowly up until a point where it is hanging around 500 MB ram free. Check the picture below. 3. When trying to normally stop the server ( I use the Multicraft control panel ) it gives a [Server] KILL signal could not be sent: [Errno 1] Operation not permitted and does not save the worlds normally afterwards. 4. At times, my server crashes unexpectedly and creates crash logs with this on the top: Description: Exception in server tick loop with a stack trace pertaining to java.util.ConcurrentModificationException . The stack traces don't lead to a plugin and are all either within net.minecraft.server , java.util, or org.bukkit. Performance Pictures: Low TPS and Very High Ram Usage, only 8 hours into server uptime: https://dl.dropbox.com/u/22563933/bukkit/1.PNG World and Entity Information: https://dl.dropbox.com/u/22563933/bukkit/2.PNG The things I have already tried: Tried creating some /nolagg examines at one point to see if it is a plugin issue, however NoLagg itself doesn't even work correctly on my server so thats out of the question. Tried out the other craftbukkit mods such as Craftbukkit++. Updated ALL plugins and ensured that they are all fully compatible with 1.3.1. Removed intensive plugins intermittently to see if they may increase performance such as NoCheatPlus, Factions, ChestShop, HomeSpawnPlus. Ever since 1.3.1 came out I have been having these issues and have been doing tons of trial and error to see what can be causing it, but no avail. I have gotten to the point where I just have to ask other people for their opinions. Summary: In short, All I need is someone to help me figure out what the heck is wrong with my server, and why the performance is suffering greatly. Please someone just take a look at the information i have provided and let me know what I could possibly do to help increase my server performance and bring it back to normal.