Users randomly being teleported to random areas underground (but never me)

Craftbukkit bersion git-Bukkit-0.0.0-949-g25c4dd8-b1025jnks (MC: 1.7.3)
just today redownloaded all the latest versions of the plugins and bukkit/craftbukkit
Windows 7 64-bit
Java Version 1.6.0_23
No Wrappers


Plugins:
AdminCmd
BigBrother
CustomCrafting
DefaultPermissions
ExactSpawn
HomeX
NoCheat
NoFire
NoRegen
NoWeather
NSCommand
OtherBlocks
PerformanceTweaks
Permissions
PlgSetspawn_op
Prefixer
Silence
SimpleChestLock
TNTWarner
WorldEdit
WorldGuard
Xray Detection

Before I had SpawnX instead of exactspawn/plg setspawn and it was still occuring.
I removed HomeX and SpawnX before and it was still happening.
I have no other ops/admins/mods.
This was happening with my 953 server version to, before I updated + redownloaded everything.

Do you guys know what could be causing this?
It's always my users, NEVER me, they're being teleported to random areas underground at random occasions (sometimes in caves, sometimes in water, sometimes suffocating, but ALWAYS underground) (exploring, walking home, etc).

 

Our server is also having this issue, only the Server Admin hasn't experienced it and I haven't experienced it since I was given admin-permissions.

Often being teleported up to 10 tiles away into solid rock and other various things causing suffocation, sometimes avoided by logging out on getting the bug and relogging in teleporting you to the next available non-suffocating tile or above ground.

We currently run the following plugins from your list:

We have recently added PerformanceTweaks and since then it's been occuring 'alot' more often.

Edit: Removed PerformanceTweaks and so far no teleporting into walls.

 

Ahh so it was performancetweaks..