Website Cache Warmer

PageSpeedPlus Cache Warmer prerenders a list of URLs on your website so they are cached allowing subsequent page loads from real users to be faster. 

Cache Warming is easy to enable and can be triggered on a schedule or on demand. It can be run on a handful of URLs or your entire website. You get to choose the location where the warming executes from. If you want to cache warm in multiple places, 11 are available. 

The warming scripts execute on our servers so it works on any website regardless of platform. This means it’s perfect for Wordpress, Magento, Drupal and any other CMS or eCommerce system.

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Contents

• What Is Cache Warming
• PageSpeedPlus Cache Warmer
• Frequency
• How To Activate
• Locations and plans
• Benefits Of Cache Warming
• Cache Warmer For Wordpress
• Conclusion

What is Cache Warming

When a web page loads many things need to happen. 

First, a request must go from a user's browser, all the way to your servers, (which could be on the other side of the world) and back again. Database queries execute and API calls to fetch additional information from external sources might be required. The retrieved data is passed into a template for the page to be rendered and sent back down the wire to the user's browser.

This server processing can take time and cause a slow page load, which infuriates users and results in them leaving. Additionally, the speed metrics such as TTFB and LCP will be poor, which results in bad Lighthouse scores that ultimately impact search rankings.

For a news website or blog, the same information is shown to all users so running database queries on every page load is actually a waste of computing cycles. The page can be fetched once, cached and then served to all users until the cache is cleared. Cache Warming occurs when a URL is requested by a Cache Warming Script solely to trigger the background server processing, retrieve the data and cache it. This gets the slow page load out of the way early so the next user visiting the site gets served a fast response from the cache. 

PageSpeedPlus Cache Warmer

The PageSpeedPlus Cache Warmer works by spinning up a headless browser and hitting the specified URLs to generate the cache, which can be either Monitored URLs or Full Site.

Monitored URLs
These are the high-value URLs for a site that are manually chosen by you to receive detailed analysis and monitoring. 

Full Site
Full Site Cache Warming loads every page on your website by using the sitemap.xml as a reference to cycle through every URL.

This takes longer than a Monitored URL scan as the number of pages is much larger. 

When a new cache warming run is triggered, the URLs goes into a queue and are processed in batches. Progress can be tracked in the website details page. Once complete, a report can be viewed showing the full list of URLs and the HTTP status code so you can ensure all pages were hit successfully.

Frequency

The Cache Warmer can be executed on a set schedule or on demand when you decide. 

Scheduled
Scheduled warming can be set to run hourly, daily, twice daily and weekly. Simply select a frequency in the site settings and automated scripts will take care of the rest.

On-Demand
On-demand takes things one step further by giving you control to decide when to trigger a cache warm. This can be done via a button in the dashboard or through an API request. 

On demand Cache Warming is designed to be triggered as part of a CI process such as after a new code deployment. Just ping our endpoint with your Site ID and we will hit the URLs within seconds of receiving the request so the slow page load is out of the way before a real user comes to the page. 

How To Activate

To activate caching warming via the UI:

• Go to the website settings in your account.
• Open the edit page and scroll to the cache warming section
• Choose a warming frequency

To activate caching warming via the API

• generate an API key in your dashboard
• make a request to https://app.pagespeedplus.com/api/site/cache-warm/start?site_id=XX&scope=monitored

A sample request is available in our API docs

That's it. The URLs for the site will now be pinged in all of the locations specified in your website settings. The result of the Cache Warm can be viewed in the site dashboard. There’s no need to mess around with cache warming scripts or execute commands. Everything is ready to use at the click of a button.

Locations and plans

Cache Warming is available on standard plans and upwards:

The locations available are:

• Dublin
• Tokyo
• California
• Montreal
• Sydney
• Frankfurt
• London
• Virginia
• Ohio
• Oregon
• São Paulo

This is the current list of locations. More will be added in the future.

Benefits Of Cache Warming

Speed locally
Websites are faster for users when the cache is warm. There's no hanging around for a slow database query to finish or an API call to complete. The page is prerendered and primed in the cache ready to be viewed. 

Speed globally
Warming can avoid latency from long round trip times such as a user in Australia requesting a site hosted in the UK. Global caching can be achieved with a CDN cache, which stores a page in the region it was requested. PageSpeedPlus Cache Warmer can fire from multiple locations and allow a copy of your site to exist in lots of locations around the world.

Avoid cache eviction
CDN caching of static HTML pages is a popular technique for accelerating page loads but this strategy can be hard to stay on top of because websites are always more popular in some regions compared to others. CDNs evict rarely requested items from their cache in favour of more popular content so even if you have lots of traffic in the UK, it doesn't mean your site will be cached in Australia. Cache Warming with PageSpeedPlus ensures your pages are requested regularly from multiple countries so they are cached in lots of places around the world at any given time. 

Control
Most cache strategies only have control over what gets cached but not when because they require a user to request a page for the first time cache. Aside from giving a poor experience to that user, there's no way to make someone come to the site. Cache Warming gives website owners total control of what and when pages get cached. 

Improved Speed Metrics
Accelerating pages means all of the metrics associated with performance will improve such as Lighthouse and Web Vitals. Unlike other techniques to improve speed, all of this is achieved without code changes in your application .

Cache Warmer For Wordpress

The features PageSpeedPlus and benefits listed above make it the ideal Wordpress Cache Warmer. Other caching warming solutions exist for Wordpress but these are plugins that need to be installed in your site.

With those, the cache warming scripts run on your own server which puts it under load that could actually slow down the site temporarily. There is also the overhead and security concern of yet another plugin to manage.

PageSpeedPlus bypasses these concerns because it executes on our servers and visits the publicly available URLs of your website.

Cache Warmer For Magento

PageSpeedPlus is also a great Cache Warmer for Magento stores. We have to say the existing Magento Cache Warming solutions are designed well.

However, similar to Wordpress, they must be installed as an extension and run on your own systems and require a high risk change to be made, which is that the exec() function needs to be enabled. This command opens the door for commands to be executed in your environment so if there is a vulnerability anywhere in your site, it could be exploited.

Final Notes On PageSpeedPlus Cache Warmer

Our Cache Warmer accelerates your website for all users and with the right approach can ensure it's fast globally.

Signing up to PageSpeedPlus activates automated cache warming immediately. If you want more control, On Demand Cache Warming can be achieved with a simple API request that can be added to your deployment process. Best of all, minimal configuration is required and it's a lightweight process that runs in the background.

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