Delightful Downloads Not supported 4.9.1

Hi
this plugin is not working properly with wordpress 4.9.1 and take too much time to execute the mysql query. Due to this it consume more resource on server and stuck the site. Please provide us support for this.

SELECT ID FROM ca_ddownload_statistics
WHERE status = ‘success’
AND post_id = 38198
AND date > DATE_SUB(‘2018-01-06 02:27:54’, INTERVAL 3 MINUTE)
AND user_ip = ‘@??1’

SELECT ID FROM ca_ddownload_statistics
WHERE status = ‘success’
AND post_id = 36259
AND date > DATE_SUB(‘2018-01-06 02:28:00’, INTERVAL 3 MINUTE)
AND user_ip = ‘Y?’

SELECT ID FROM ca_ddownload_statistics
WHERE status = ‘success’
AND post_id = 38198
AND date > DATE_SUB(‘2018-01-06 02:28:02’, INTERVAL 3 MINUTE)
AND user_ip = ‘1#@’