Bukkit

What steps will reproduce the problem?
I have a mix of holographic shops and NPC shops on my server. However, when I try to run the server with this mod installed I get very severe lag and errors/warnings in my logs caused by this plugin.

I know this is caused by the better shops plugin because removing the plugin completely fixes the lag issue. And reinstalling it causes the server to lag badly again.

What version of the product are you using?
2.1.2 and 2.1.1, I tried updating to newest version to fix it but it did not help.

Do you have an error log of what happened?
Yes
http://pastebin.com/yF8qDFGj

Please provide any additional information below.

A little lag would be fine, however this lags the server so badly that the mobs freeze in place every two steps and have a 3-5 second delay before responding to anything.