Bug Description

AMP plugin create preview link in admin menu with function amp_admin_get_preview_permalink
But it makes get_posts call which costs a lot especially in WordPress with many posts:

As a result, users face slow page loads on every admin page.
In my case, the query costs almost 3 seconds.

Expected Behaviour

1. Customizer link should be always same(e.g. https://example.com/wp-admin/customizer.php)
2. In customizer page of amp, default permalink which amp_admin_get_preview_permalink expected to retrieve will be applied.

Steps to reproduce

1. Install WordPress and put 10,000 posts by 100 users in 3 custom post types.
2. Install and activate AMP & Query Monitor.
3. Open admin page and confirm slow query runs at every page.

Screenshots

Additional context

• WordPress version: 5.2.4
• Plugin version: 1.4.0
• Gutenberg plugin version (if applicable):
• AMP plugin template mode:
• PHP version: 7.2
• OS: Amazon Linux
• Browser: Chrome
• Device: Macbook Pro

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Acceptance criteria

Implementation brief

QA testing instructions

• Set AMP website mode to 'Reader' (so that the AMP Customizer menu item is shown):

  

• Clicking on it should send you to the homepage, and not the first AMP compatible post

Demo

Changelog entry