vlookup creates large cache

We have an Excel file which quotes are generated from. This references several data files using vlookup.
The problem is when the master file is saved with data in it the file size is very large e.g. >1Mb even though only a few cells are populated. When a PC is taken off the network the vlookups still work meaning that somehow the background files are being cached.
How do we save the file and make the data returned static so that the file size is smaller - even though the vlookup will not work any more.

I would use Access for large data bases, look into it.