Hello there, for some reason my server lags at random times, and this is not normal lag, for it lags for an extended period of time (give or take about 5-10 seconds) then the server crashes.

Some Info:
RAM: 1 GB

Players When This Occurred: 3 (Sadly, I have no idea why)

Plugins (30): Citizens, NoPluginStealers, GroupManager, AlphaChest, Liquid, WorldEdit, Enjin_Minecraft_Plugin, BukkitCompat, mcore, HealthBar, Multiverse-Core, WorldGuard, BookRules, Lockette, ClearLag, ScheduledAnnouncer2, ProtocolLib, HolographicDisplays, mcMMO, Essentials, EssentialsProtect, EssentialsSpawn, MagicSpells, DisguiseCraft, CompatNoCheatPlus, EssentialsChat, Factions, NoCheatPlus, PlayerHeads, CombatLog

What Set It Off: No Idea

Other Notes: This happens randomly and I have no idea why. The error that pops up is that stupid io.netty.handler something error, and it's always been like this, even when we have had less plugins than this, like about 5 plugins. Any help? NO ERRORS SHOW UP IN CONSOLE EITHER!

Host: Unlimited Kingdoms if that's important