Pulling Data from unopened Excel Spreadsheets with external connections

My spreadsheet is getting very large. I have a large list of companies, 4000+ with live connections to the ones that are in the S&P 500 pulling down external data. The point of the entire project is to have this live information feed to an editable interface for the user. It is working so far, however, the large amount of referrence data is slowing down the opening/manipulation process. I would like to move the referrence material off the interface to a file in the background to decrease the size of the wkst. I tried this and it took even longer to load and update the live information.

Is there anyway to make this work faster/more efficiently? Any suggestions? Thanks in advance, and please let me know if more information is needed.

-Nate