Weird server lag

[acsdog]

So I host a custom mod pack server, with the following mods: PetroGen, Additional Pipes, Advanced Machines, Applied Energistics, All the UE mods (except for ICBM), BC3, IC2, EE3, Backpack Mod, Biblio Craft, Compact Solars, CC, CCsensors, Extra Biomes XL, Forestry, Gravitation Suite, IC2 nuclear control, Iron Chests, Jammy's Furniture, Mekanism, MineChem, MFR, Modular Powersuits, Omnitools, Paintball, Portal Gun, Power Converters, Railcraft, All of red power (except for micro blocks), Secret rooms, soul shards, Steve's carts, SyntaCraft, ThaumCraft, Thermal Expansion, Tinker's Construct, Useful Food, Wireless redstone (ChickenBones), XReliquary, and xycraft. I gave it 1 GB of ram, and even with 3 people on it, I only use about 25% of that. The average tick time is about 20-25 ms with 3 people, and my upload speed is 10Mb/s. The world is fresh, so there aren't any lag-inducing machines yet. I have no idea why it is lagging. I break a block and it disappears, then re-appears 1 second later, then disappears again. The mobs are very slow, and there is just overall lagginess. I am using Hamachi, but I have never had this problem before. Any ideas?

[bigb99100]

check if you CPU usage is @ 100%. if it is then we found the source of your lag.if not then it might be hamitchi.