Regions. how can I disable a region? (not disabling blocks)
The context module is a very handy way to control blocks on a site which uses them extensively. It allows you to define contexts which show and hide blocks. It will stop the blocks from even being loaded so will help performance. 

It makes it much easier to define where and when the blocks appear. Rather than defining things per block you define what blocks appear per context.

This video seems to explain things well.