I am experiencing this as well – seems it started over the last couple of weeks. And only affects dashboard performance but it is painful to make updates to the point where I have to disable the plugin until I finish making website updates.
I installed Query Monitor and the only warnings I get from it are in relation to this plugin. It reports these queries as being the culprits (times vary, but always slow):
QUERY:
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = ‘wp_pqwdpg_mlw_quizzes’
AND column_name = ‘quiz_author_id’
CALLER:
do_action(‘admin_init’)
COMPONENT:
Core
ROW:
1
TIME:
20.7019
QUERY:
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = ‘wp_pqwdpg_mlw_results’
AND column_name = ‘unique_id’
CALLER:
do_action(‘admin_init’)
COMPONENT:
Core
ROW:
1
TIME:
7.7581
