Hi,

A question for those of you who have experimented with this.
I want to implement some heavy duty mathematical processing which is
accessible from an excel front end.

As I understand it my options a

1. Pure VBA functions (very slow but compatible with all versions of
excel from excel 97 upwards)
2. Pure C/C++ dll with wrapper functions in VBA (much faster but still
relatively slow for large worksheets with many cell formulae - again
available in all versions of excel 97 upwards)
3. A COM dll with wrapper functions in VBA (same as 2 above except
allows use in other projects such as a VB project - eughhh - I know -
I don;t see that as a plus either)
4. A COM dll which can be seen straight from worksheet level (I think
excel 2002 supports this? - need guidance on this though...)
5. Good old fashioned xlls in pure C/C++

I've sort of discounted options 1 and 2. What I'm really left with is
a core set of DLLs with an interface of an XLL or a COM DLL.

What I really want to know is do people find COM slower in terms of
real speed - especially if anyone has experimented with option 4
compared to 5.

And are Xlls deprecated in favour of COM?

(My gut preference is XLLs - I just don't trust COM for speed; Xll
coding is a bit dirty but not in a way that seems to kill speed)

(and btw has anyone had problems with compiling their Xlls with Visual
Studio .NET 2003 and its treatment of string literals?)

Any suggestions/guidelines/criticism would be much appreciated.

Thanks in advance,

M.