Blocks list in admin is really slow

The blocks list in admin (/wp-admin/edit.php?post_type=wp_block) is really slow to display when there is a lot of reusable blocks on the site.
For example, with 422 blocks, blocks list take 30 seconds to load, with 20 blocks per page set in screen settings.

Using Query Monitor plugin, it appears that the function reblex_reusable_screen_fill_column() which is called for each block in the list, take 1,5 second for each block.
The slow request is :

SELECT *
FROM wp_posts
WHERE post_content LIKE '%<!-- wp:block {"ref":22881}%' and post_type NOT IN ('revision', 'attachment', 'nav_menu_item')

.