Long delay when loading the post editor

The plugin introduces almost 40 second delay when I load the “Edit Post” page in the admin UI. It makes over 50 database queries similar to the one below. I used Xdebug and Query Monitor plugin to track these queries down. Each query takes just under a second.

Why is it loading so much data? Is it trying to do something that should be done as part of a cron?

SELECT main_posts.ID
FROM main_posts
LEFT JOIN main_postmeta
ON (main_posts.ID = main_postmeta.post_id
AND main_postmeta.meta_key = 'wp-smpro-smush-data' )
WHERE 1=1
AND (main_posts.post_mime_type = 'image/jpeg'
OR main_posts.post_mime_type = 'image/gif'
OR main_posts.post_mime_type = 'image/png')
AND ( main_postmeta.post_id IS NULL )
AND main_posts.post_type = 'attachment'
AND ((main_posts.post_status <> 'trash'
AND main_posts.post_status <> 'auto-draft'
AND main_posts.post_status <> 'autoresponder'))
GROUP BY main_posts.ID
ORDER BY main_posts.ID DESC
LIMIT 72000, 2000

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