Completion cron task very slow when has more than 100k users

SELECT

	c.id AS course,

	u.id AS userid,

	crc.id AS completionid,

	ue.timestart AS timeenrolled,

	ue.timecreated

FROM

	{user} u

INNER JOIN

	{user_enrolments} ue

 ON ue.userid = u.id

INNER JOIN

	{enrol} e

 ON e.id = ue.enrolid

INNER JOIN

	{course} c

 ON c.id = e.courseid

INNER JOIN

	{role_assignments} ra

 ON ra.userid = u.id

LEFT JOIN

	{course_completions} crc

 ON crc.course = c.id

AND crc.userid = u.id

WHERE

	c.enablecompletion = 1

AND crc.timeenrolled IS NULL

AND ue.status = 0

AND e.status = 0

AND u.deleted = 0

AND ue.timestart < ?

AND (ue.timeend > ? OR ue.timeend = 0)

	$roles

ORDER BY

	course,

	userid