Server Crashes then players lose items?!

I'm having this problem lately where the server all of a sudden freezes.

There is this error in the console.

Code:

27.07 19:42:09 [Server] SEVERE at net.minecraft.server.NBTBase.b(SourceFile:77)
27.07 19:42:06 [Server] SEVERE at net.minecraft.server.NBTTagByteArray.load(SourceFile:25)
27.07 19:42:04 [Server] SEVERE java.lang.OutOfMemoryError: Java heap space

After the crash, players are complaining that some of their items are gone that were in their inventory.

Here are my plugins:

Code:

27.07 19:52:13 [Server] INFO Plugins (44): LagMeter, Orebfuscator, GroupManager, Ptweaks, WorldEdit, NoCheatPlus, NoSwear, Buycraft, PvPTime, War, Vault, CustomJoinMessage, Restarter, MobBountyReloaded, MyHome, ConsoleSay, WorldGuard, TreeAssist, SignColours, SimplyVanish, RAM, iConomy, AutoKick, OnTime, ReportRTS, CoreProtect, Permissions, LimitedCreative, Honeypot, BKCommonLib, N3W_TheEndAgain, FirstJoinPlus, SimpleSpleef, Votifier, AutoSaveWorld, AutoAnnouncer, Essentials, EssentialsSpawn, LWC, ChestShop, EssentialsChat, Residence, Factions, ResidenceSigns

Does anyone have any suggestions to fix this? I'm unable to add more RAM. So any other options?

 

Each plugin can use up more RAM than others.
To me, it sounds like your only 2 options are to either add more RAM, or remove some plugins.

 

What plugins do you recommend I remove?

 

Don't ask me. It all depends on each plugin and their configurations.
How about you try it and do some of your own research?