jj2007, some more stuff about the problem on this subject : viewtopic.php?t=24648
Arrays are fast till you do not need to many redim otherwise using list appears to be usually a better choice.
Arrays are faster seeking than lists up to a specified numbers of values depending on the hardware specifications
The choice between array vs list will be depending on the size of the datas the algo needs to manage, the size the available memory, the way the memory is managed by system.
In Lists the purpose is to avoid as far as possible cAllocate, Deallocate or any low level reallocation.
This a crucial point when using cascaded indexation (a tree to access keys values)
So far, accessing a key "123456" is much more faster when accessing "12" then "34" then "56" in a tree structure because less lookups on values compared to a flat list, drawback is memory allocations/réallocations/deallocations slowing the system as the tree structure needs to be recomputed/maintained.
The more values in a list, the more the indexed (tree) structure will outperforms a flat list.
Other hand : the more the allocation is used, the more the system is sollicited at low level.
Problem is same with indexed arrays : Redim is slow
Conclusion :Arrays vs List appears to be a question of optimization : both are usefull.
ps : St_W, I'm currently trying to go as fast as possible, hardest looks like behind me, stable & tested version planned within 2-3 months.