Matt Curland's "Advanced Visual Basic 6: Power Techniques for Everyday Programs: Hardcore Programming Techniques" was a cracker of a book as well back in the day:
another example of poor teardown code.
DAO has Close methods that must be
called in the correct order, and the
objects must be released in the
correct order as well (Recordset
before Database, for example). This
single poor object model behavior has
led to the misconception that VB leaks
memory unless you explicitly set all
the local variables to nothing at the
end of a function. This is a
completely false notion in a
well-designed object model. VB can
clear the variables faster at the End
Sub line than you can from code, and
it checks the variables even if you
explicitly release your references.
Any effort you make is duplicated.
Column major. VB6 uses COM SAFEARRAYs and lays them out in column-major order. The fastest access is like this (although it won't matter if you only have 30x30 elements).
For i = 1 To 30
For j = 1 To 30
myarray (j, i) = something
Next
Next
For instance accessing a 2D SAFEARRAY is considerably slower than accessing a 1D SAFEARRAY, so in order to set all array entries to the same value it is quicker to bypass VB6's SAFEARRAY descriptor and temporarily make one of your own. Page 33.
You should also consider turning on "Remove array bounds checks" in the project properties compile options.
https://www.amazon.co.uk/dp/0201707128
Matt Curland, author of Advanced Visual Basic 6, who knows more about Visual Basic than most of us ever will, thinks it is wasted effort. Consider this quote (p110) about DAO, the COM data access library that primarily targets the Access Database Engine:
Do you need to call COM methods on this DLL? If so, I'm not at all sure this is possible.
Matthew Curland's excellent Advanced Visual Basic 6 is the first place I'd look, though. There's some powerful under-the-hood COM stuff in there that circumvents the normal VB6 techniques.
There's also DirectCom, which allows you to call COM methods without using COM. Never used it myself, but people chat about it on the VB6 newsgroup.
Column major. VB6 uses COM SAFEARRAYs and lays them out in column-major order. The fastest access is like this (although it won't matter if you only have 30x30 elements).
If you really want to speed up your array processing, consider the tips in Advanced Visual Basic by Matt Curland, which shows you how to poke around inside the underlying SAFEARRAY structures.
For instance accessing a 2D SAFEARRAY is considerably slower than accessing a 1D SAFEARRAY, so in order to set all array entries to the same value it is quicker to bypass VB6's SAFEARRAY descriptor and temporarily make one of your own. Page 33.
You should also consider turning on "Remove array bounds checks" in the project properties compile options.