From page Signshop have sent me here because they believe it is an error of vault
https://dev.bukkit.org/bukkit-plugins/signshop/tickets/689-grave-error-and-lag/

Spigot 1.8.8
Vault: 1.5.6-b49
SignShop version: 2.11.0Dev (latest dev)
Essentials manages the economy (EssentialsX 2.0.1)
ZPermissions 1.3

It is a mistake that leads days appearing on the console and causes the server to go very slow when it occurs

I imagine that is when a user clicks on a sign but do not know what it is or where it is
Clarify that in some specific cartel, others are good, but I can't get to find him

http://pastebin.com/vpM3tpAu

This means your server is not setup properly, or the creation of accounts is failing. the codeblock in the Essentials connector was requested to be done like that per Essentials.