I'd like to increase to 5000 the friend load limit in each single click of "More friends"
Changing
friendloadlimit= 5000 in default.ini

doesn't seem to work.

Any idea why?

Hi,

we hardcoded it at javascript as 200, I suggest you to changing it from php code:
/components/com_community/controllers/system.php at line 66 you can see this code

public function ajaxLoadFriendsList($namePrefix, $callback, $cid, $limitstart = 0, $limit = 200) {

if ($limit == 200) $limit = 500;