Divide Large Data Blob?

[Rick Harrison]

I have a large chunk of data that I want to
search as quickly as possible.  

Unfortunately the part I want to search is the 
middle third of the data.  The other thirds at 
the beginning and at the end are just junk and 
slow down my search so I want to get rid of them.

I don’t want to search line by line as that
takes way too long.

There’s no unique character dividing any
of these data regions.

What’s the best way to do this?

Thanks in advance!

Rick