Course section collapsing sends way too many AJAX requests

Moodle currently sends (number of sections + 1) AJAX requests when clicking the collapse / expand all button, and 2 requests when collapsing / expanding a single selection. Also, only the last request contains the correct list of collapsed sections (all other requests have an empty list) and those requests are send simultaneously , so if the last request is not processed as the last on the server, the course will be fully expanded on the next reload.