Hope you folks out there can help me out with suggestions here.

I am about to write a management accounts reporting pack for a
reasonably large company. Their trial balance is 16,000 lines long and
downloads usually include This Year Month, This Year to date, Budget
month, Budget YTD, Prior Year Month, Prior Year To date so its a fair
bit of data. The reporting pack is likely to be 40 - 50 pages of
analysis, summaries, P&L, Balance sheets, Cash Flows, etc., which read
directly off the TB download. There would also be some intermediary
calculations on some sheets (eg to provide a "per unit" analysis of
P&L) - [unit volumes is the only other data entry required]

I know that I can produce it in excel but I fear that it may become too
big & slow.

Can anyone suggest what might be a good way to build this pack which
would result in it running quicker. eg store data in Access and link
excel via pivot tables OR perhaps there is some good OLAP add-in for
excel?? I am open to all ideas and don't mind if I have a learning
curve or some new software to buy.

Kind regards

Stuart