https://bugs.openldap.org/show_bug.cgi?id=10041
--- Comment #3 from David Coutadeur david.coutadeur@gmail.com --- The given patch (https://git.openldap.org/openldap/openldap/-/merge_requests/617.patch) seems to fix the issue!
On a new machine, with a fresh-compiled standard OpenLDAP 2.5.14: ~99s
ldapsearch -x -H 'ldap://localhost:389/' -D 'uid=admin,ou=people,dc=my-organization,dc=com' -w 'secret' -b 'ou=groups,dc=my-organization,dc=com' '(&(objectClass=groupOfNames)(member=uid=user1,ou=people,dc=my-organization,dc=com))'
slapd[151155]: conn=1000 op=1 SEARCH RESULT tag=101 err=0 qtime=0.000049 etime=99.383118 nentries=1 text=
On the same machine, with a fresh-compiled OpenLDAP 2.5.14 + 617.patch: ~2.6ms
ldapsearch -x -H 'ldap://localhost:389/' -D 'uid=admin,ou=people,dc=my-organization,dc=com' -w 'secret' -b 'ou=groups,dc=my-organization,dc=com' '(&(objectClass=groupOfNames)(member=uid=user1,ou=people,dc=my-organization,dc=com))'
slapd[220887]: conn=1000 op=1 SEARCH RESULT tag=101 err=0 qtime=0.000053 etime=0.002617 nentries=1 text=
Thanks for the quick fix Ondrej and Howard! Could you consider applying this patch also on OpenLDAP 2.5 branch?