Severe SQL performance issue caused by core_course_category::get_nearest_edit...

Hello all,We are facing severe performance degradation on our Moodle 4.5.7+ (Build: 20251017) installation at Aix-Marseille University (France).This seems to matchMDL-81304 – “Still very poor performance on my/courses.php”.EnvironmentMoodle version: 4.5.7+ (Build: 20251017)MariaDB10.6.22~120k users, ~2k course categoriesSymptomsOn both theDashboardand My courses pages, the functioncore_course_category::get_nearest_editable_subcategory()triggers heavy UNIONSQLqueries (about 20 seconds each) for every user, including students who don’t have course creation or management capabilities.These queries end up saturating the database’s CPU and memory, causing major platform-wide slowdowns.Workaround appliedWe temporarily commented out both function calls in:my/courses.phpblocks/myoverview/classes/output/main.phpThis immediately restored normal performance, but it’s only a short-term fix.If anyone else is experiencing the same behavior on Moodle 4.5.x, please vote or comment onMDL-81304.The more evidence we can provide, the better our chances of getting a timely fix in the 4.5 branch.Thanks in advance for your input.