Chunking my voxel terrain

Can anyone tell me an idea on how to chunk my voxel terrain. I have seperate gameObjects that dont render when the player is far away.
this works fine until the player starts moving which cause a HUGE spike in lag. so if someone can tell me how to fix this with chunks, please respond.

thanks

btw i dont want to use one modifieible mesh

 

I highly suggest this thread:

http://forum.unity3d.com/threads/63149-After-playing-minecraft...

The whole "Block Engine Demystified" series from the developer of Block Story is great
http://www.blockstory.net/node/56

Let's make a voxel engine is also a great tutorial series, though not directly related to Unity - the basic concepts hold true no matter what environment you're working in.
https://sites.google.com/site/letsmakeavoxelengine/