• I've read and understood the contribution guidelines.
• I've searched for any related issues and avoided creating a duplicate issue.

Please give us a description of what happened.

When I upgraded my website instance of Yoast SEO 7.0.1 to 7.0.2, the average time to first byte (TTFB) increased on all the website pages increased by 50 - 70% (as recorded using Google Chrome Developer tools).

Please describe what you expected to happen and why.

Not increase time to first byte.

How can we reproduce this behavior?

1. Enable a default theme (E.G. Twenty Seventeen).
2. Install Health Check plugin.
3. Enable troubleshooting mode.
4. Disable all plugins.
5. Using Yoast SEO 7.0.1 check the home page TTFB using Google Chrome developer tools, refresh several times to establish an average.
6. Using Yoast SEO 7.0.2 check the home page TTFB using Google Chrome developer tools, refresh several times to establish an average.

Steps I undertook to validate issue

1. Cloned the live website to a local environment (changed from Nginx to Apache).
2. Installed Health Check plugin.
3. Enabled troubleshooting mode.
4. Disabled all plugins.
5. Switched the theme to Twenty Seventeen.
6. Enabled only Yoast SEO 7.0.1 and performed 5 refreshes on the home page.
7. Enabled only Yoast SEO 7.0.2 and performed 5 refreshed on the home page.

TTFB statistics

Yoast SEO 7.0.1

1. 472ms
2. 466ms
3. 438ms
4. 477ms
5. 455ms

Yoast SEO 7.0.2

1. 798ms
2. 715ms
3. 746ms
4. 718ms
5. 709ms

These statistics represent a local environment with no caching. On the live website, with OPCache enabled, the difference was, on average, 280 - 420ms for 7.0.1 and 420 - 780ms for 7.0.2.

Technical Info

Live Website Details

• WordPress version: 4.9.4
• Yoast SEO version: 7.0.2
• Web server: Nginx
• PHP: 7.2.2
• MariaDB: 10.1.14
• Theme: Custom
• Caching: OPCache

Local Website Details

• WordPress version: 4.9.4
• Yoast SEO version: 7.0.2
• Web server: Apache
• PHP: 7.1.7
• MariaDB: 10.1.25
• Theme: Twenty Seventeen
• Caching: None (disabled for testing purposes)