>>Not sure if I understood you correctly, you meant that if you run it with adir() the speed is fine in the local computer (the server) but slow if run in a work station?

Yes.

>>I am no expert, but I guess it is possible, after all adir is pulling the list of all files, not just the folders, from the server and you mentioned that some of this folders have thousands of files

but am not trying to get all files in the directory but only folder names see my command below
=ADIR(larr,'','D') && am doing this
=ADIR(larr,'*.*','D') && not this