(Why) Does the number of folders/subfolders decelerate strongly the folders management ?

Hello,

As i have many folders / subfolders* **, the creation and the move *** of the new folder is slower and slower;
and i fear it's going soon to be impossible to create any more folder, because i've already problems with delay on the server;
that's why i put this post in "bug report".

* because files appears much more quickly (less than 10 in a folder) when there are many [also when using CKEditor/CKFinder]
** here "many" means more than a thousand,
*** i have to do because the new folder doesn't appear in alphabetical order in Media Browser, though of course it is on server.