Well, yes. I do lots of things with Excel. I'm currently working on two
investment control systems that use Excel as the front-end to overseas
Sybase databases.

However, I stand by what I said. Excel VBA (and Word VBA, etc) are not
fully-fledged programming environments and in particular do not provide the
optimisations and efficiencies that make handling large amounts or data
efficient.

VBA IS inherently slow. In many cases this isn't noticeable (or isn't a
worry), so go ahead and use it.

However, some jobs do require a special environment. For instance,
compute-intensive jobs do not run efficiently in interpreted or
semi-compiled environments such as VBA.

I think the whole point is that the user isn't happy with the performance,
as indicated in the original question.