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The Rebirth of FlyingPress: Introducing v4

V4 Release

Today marks the next beginning of FlyingPress.

If you’ve been keeping an eye on our updates, you might have seen that we’ve been making only small enhancements and bug fixes in the last few months. But, for those who have been with us since the early days, you know how fast we innovate.

We hit a roadblock with our HTML parser, the library we relied on, which caused a significant increase in support requests and left our team bogged down with fixing customer website issues instead of focusing on improving FlyingPress.

Realizing the impact of this challenge, we took immediate action by hiring more engineers and starting from scratch to rebuild FlyingPress.

What’s new in v4?

Custom HTML parser

Previously, we relied on third-party HTML parsing libraries to parse HTML and implement various optimizations. This helped us build features quickly, but these libraries had their drawbacks – for example, they sometimes parsed HTML incorrectly when it contained invalid tags, and also required higher resource usage on servers, especially on shared hosting.

After months of hard work, our engineers have developed a custom HTML parser specifically designed to meet our needs. This has resulted in an incredibly fast parser that can handle invalid HTML with minimal resource usage.

Lightning-fast & improved removal of unused CSS

FlyingPress was the first WordPress plugin to introduce automatic removal of unused CSS. With version 4, we’re taking it to the next level. Our engineers have created a new engine with a custom-built CSS parser to remove unused CSS even faster.

Results: FlyingPress can now remove unused CSS from complex pages in less than 30 milliseconds with minimal resource usage. It will remove unused CSS from every post and page on every preload.

We have also removed the “Purge Used CSS” button. 😉

Preload cache, without purging!

With FlyingPress version 4, you can preload your cache without purging it. As you preload, existing cached pages will be overwritten one by one instead of purging the entire cache. Visitors will continue to see previously cached pages until the new cache is generated.

If you prefer to purge first and then preload the cache, this option is still available with just one click.

Always on Caching

Previous versions of FlyingPress allowed you to disable page caching if desired, especially if you were using external caching layers such as Nginx, Varnish, or Cloudflare APO. However, this often causes conflicts, confusion, and decreased performance for real visitors as most of these external caching layers cannot preload cache.

FlyingPress version 4 now always caches pages, serving as a fallback cache if the external caching layers do not have the cached page, thereby maintaining a high cache hit ratio.

Delay all JS files or only selected

FlyingPress has always had the option to delay selected JavaScript files and load them on user interaction, pre-filled with common third-party scripts. However, many customers have websites that can render above-the-fold without any JavaScript files. With version 4, you can delay all JavaScript files for even better performance.

Responsive interface

The FlyingPress dashboard is now fully responsive, allowing you to configure, purge, and preload from anywhere, even on mobile devices.


For developers

FlyingPress v4 comes with many filters, actions, and functions that developers can use to customize FlyingPress further. You can find all of these resources in our documentation at

Other improvements

  • Caching for logged-in users
  • Caching URLs with query strings, including search page
  • Option to bypass cache based on custom cookies
  • Exclusion of stylesheets from unused CSS removal
  • Improved handling of responsive images, excluding above-the-fold images
  • Enhanced YouTube video placeholder

Upgrading from v3

We highly recommend trying the upgrade on a staging site before installing in production.

Please note that you may need to set up your configuration again after upgrading to v4.

What’s next?

By FlyingPress v4, we’ve a new strong foundation that helps to build robust features quickly and efficiently.

Here are a few things we’re planning:

  • Automated purging of external caching layers
  • Multilingual support
  • Integrating various CDNs
  • Expanding our support team
  • Import/export settings
  • Remove WordPress bloat

We hope that our users will appreciate these changes and experience the benefits of faster, more efficient websites. Additionally, with a focus on development, we will continue to improve and expand our offerings, making FlyingPress the best choice for your website’s performance optimization needs. Upgrade to v4 today and see the difference for yourself!

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