Putting the code in a VB6 ActiveX dll can make it faster as well and has the
benefit that it is very easy.
The other thing is to look at are the functions themself and see if they can
be speeded up.
Maybe it is worth to post them here.

RBS

"Ben" wrote in message
...
Hi There

I need to add some User Defined Functions to Excel 2003 - the functions
are
CPU intensive.

The existing spreadsheet has the functions written in Excel VBA (as an XLA
add in), and they are very slow.

What are my choices ? Is this correct:
(1) Write an XLL in C++
(2) Write a COM Add in in C++
(3) Write a COM Add in in C#
(4) Write an Automation Add In in C#

Has anyone done any comparisons on the performance of XLL's in C++ versus
Automation Add Ins in C# ? I suppose C# is a great deal slower because of
the Interop ?

TIA