Which one of this plugins could be causing network lag?

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Code:

Server information:
    Location:
        System: Windows 7 (64 Bit)
        Java: 1.7.0_02-ea
        JVM: HotSpot 64-Bit VM 20.0-b4
            Processors:            Available processors: 2
            Total Memory: 4GB
            Max Memory: 3GB
            Allocated Memory: 2GB

Other than Orebfuscator, DynMap, VoxelPort and probably WorldBorder, what else could be contributing to the network lag of my server?

The lag seems to be on and off, around every 5-10 seconds it lags for a little while. Any idea?

 

Network lag? Nothing in bukkit causes network lag. Network lag is dependent on your connection and if any other programs are running that need that connection.

 

If you wish to reduce network useage consider using Spout and have your players use spoutcraft. It comes with a cache system that reduces network useage

 

After meddling with command prompt, I found out that my server is being DoSed by "www18192u".