When users visit a website, loading speed may be one of the most important things that they care about. It directly affects the user's experience and their decision to stay or leave the website. Therefore, webmasters always try to speed up their sites. There are many methods to do it, and using cache plugins is one of them.

There are a lot of plugins to cache your website so choosing a suitable one isn't easy. In this article, let's learn about cache and top 5+ best cache plugins to speed up your website speed. To test and compare the effectiveness of them, I installed each cache plugin for my website and used a prestigious tool to see how faster and lighter my website was.

What is Cache?

First, you should learn about the way that browsers display websites' data. It follows these steps:

• The browser sends requests to the website server to get data
• The web server receives requests then finds and processes data from its database
• The web server sends data back to the browser (data in the form of HTML)
• The browser receives data and displays them

This process will repeat whenever the browser needs to retrieve data from the web server. These repetitions can make your website run slowly because the web server has to solve too many repeated requests. To reduce these repeated operations, we can use Cache.

Cache is temporary storage to contain data that is usually queried by browsers. When the web server receives a request to retrieve data, it will send data from Cache instead of finding and processing data as usual. This saves a lot of time for repeated actions. People call this process of storing and reusing data is "Caching".

To optimize the caching speed and security, Cache can be located in different places such as:

• Website servers
• Proxy servers
• Browsers

Why Should We Use Cache?

Using Cache brings us 2 main benefits:

1. Increase website loading speed: Caching reduces repeated operations, so the web server doesn't have to solve huge requests at a time. This optimizes web performance and makes your website run smoother. In addition, displaying data from Cache is much faster than querying data as usual.
2. Get a higher SEO score: Speed is one of the criteria of SEO optimization. The faster your website load, the higher SEO score it gets. So, using Cache to increase your website speed will help you get a higher SEO score.

How do the Plugins Cache Websites?

Here are the most popular techniques that plugins use to cache websites:

Browser Cache

Browser Cache is the work of making browsers store static data of a website into the computer's hard drive of end-users. It means that when someone visits a website, the browser will store the website data such as CSS / Javascript files, HTML, logo, image, background, ... The browser will use this data to display for the next time.

HTML Cache (Page Cache)

HTML Cache is storing data (that is frequently requested) as static HTML files. Many cache plugins use it as the main technique because it's quite easy and effective. HTML Cache uses quite a lot of memory to store HTML files. Therefore, it works well only on normal websites, which doesn't have so much data.

Database Cache

Database Cache is storing the results of popular requests to the database in RAM. The web server will display these data for later requests.

Opcode Cache

Opcode Cache is storing the results of PHP code into RAM or hard disk. This technique depends on Opcode systems such as APC, WinCache, XCache, ...

Object Cache

Object cache is used only for WordPress sites because this framework supplies users with the wp_cache function. You can use this function to store results of requests to objects (queries, session, ...) into RAM. To use object cache, you need to install a cache system such as Memcached, Redis, XCache, APC, ...

Top 5+ Plugins to Speed Up Your Website Speed

There're a lot of plugins to cache your website from premium plugins to free ones. We made a review and listed here the top best 5+ Cache plugins as follows:

1. WP Super Cache
2. WP Fastest Cache
3. Litespeed Cache
4. W3 Total Cache
5. WP Rocket

To test the ability to speed up websites of these above plugins, I use the GTmetrix tool. Before using cache plugins, my PageSpeed Score is F(48%) which means my website has low speed.

WP Super Cache

WP Super Cache is a free cache plugin with 2+ million active installations. It has had the most active installations on this list so far. Besides, WP Super Cache is a product created by Automattic --- the WordPress owner, so you can be assured about its quality and security. This plugin uses HTML Cache and works well on normal websites.

WP Super Cache has many useful features such as Compress page, Cache Rebuild, Don't Cache pages for known users, ... It also supports CDN and Extra homepage checks. In addition, WP Super Cache allows you to cache your website with 2 levels:

1. Simple: it's recommended level and used for normal website
2. Expert: use it when your web server usually encounters a huge traffic
3. WP --- Cache caching: use it when you want to enable cache mainly for known users, URLs with parameters and feeds

Highlight features:

• Simple caching
• Turn off page caching for known users
• Cache rebuild
• Page Compression
• Extra homepage checks
• CDN support

After using WP Super Cache, my PageSpeed Score increased from F(48%) to B(87%).

WP Fastest Cache

WP Fastest Cache is a freemium and easy-to-use plugin. It supports HTML Cache and Browser Cache. It won't take a lot of time to learn how to use WP Fastest Cache because this plugin has a user-friendly and clear UI. Therefore, it will be a good solution if you're a WordPress beginner.

WP Fastest Cache has many useful features such as Cache Timeout, Enable/Disable cache option for logged-in users, Preload Cache, ... In addition, it supports CDN, SSL, and Cloudflare.

Highlight features:

• Cache Timeout
• Preload Cache
• Mod_Rewrite
• Delete all cache files after publishing a post / page
• Admin can delete all cached files and minified CSS, JS from the options page
• Block cache for specific page or post with Short Code
• Enable/Disable cache option for logged-in users, mobile devices
• Support CDN, SLL, Cloudflare
• Exclude pages and user-agents

After using WP Fastest Cache, my PageSpeed Score increased from F(48%) to A (97%).

Litespeed Cache

Litespeed Cache is a powerful and freemium plugin. It supports HTML Cache, Browser Cache, and Object Cache. Besides, it has an exclusive server for Server-level Full-page Cache. This plugin is compatible with popular plugins such as WooCommerce, Yoast SEO, bbPress, ...

Litespeed Cache supports Server-Level Full-page Cache, Privet Cache, Browser Cache, HTTP/2 Push, and other useful features such as CSS/Javascript/HTML Minification, CSS/JavaScript Combination, Image Optimization, CDN Support, Lazy Load Images, Database Optimization, ...

Highlight features:

• Server-Level Full-page Cache
• Privet Cache
• Browser Cache
• HTTP/2 Push
• CSS/JavaScript Combination
• CSS/Javascript/HTML Minification
• Lazy Load Images
• Database Optimization
• Image Optimization
• CDN Support

After using Litespeed Cache, my PageSpeed Score increased from F(48%) to A(97%).

W3 Total Cache

W3 Total Cache is a feature-rich and freemium plugin. It supports all the Cache techniques I listed above. This plugin has a lot of features to fit your various needs of caching. However, it's not easy-to-use because there're so many features. You have to learn a lot to master this plugin. Therefore, it will be suitable for people that have tech-based knowledge or want to improve their skills.

Highlight Features:

• Compatible with shared hosting, virtual private / dedicated servers, and dedicated servers / clusters
• Minify CSS, Javascript, HTML, posts, pages, RSS feeds, ...
• Defer non-critical CSS and Javascript for rendering pages faster
• Cache pages and posts (that are minified and compressed) in memory or on disk or on (FSD) CDN (by user agent group)
• Cache CSS and JavaScript (that are minified and compressed) in memory, on disk or on CDN
• Caching of database objects in memory or on disk
• Caching methods include local Disk, Redis, Memcached, APC, APCu, eAccelerator, XCache, and WinCache
• Non-blocking JavaScript embedding
• Reverse proxy integration via Nginx or Varnish
• AMP, CDN, SSL Supports
• Various security features to help ensure website safety
• Extension framework for customization or extensibility for Cloudflare, WPML and more

After using W3 Total Cache, my PageSpeed Score increased from F(48%) to B(88%).

WP Rocket

WP Rocket is the only premium plugin on this list. It can fit all your needs about caching. Besides, it has many other useful features to speed up your website such as CDN Support, Lazy loaded Images. This plugin is also very easy to use. Therefore, it's a good choice for WordPress beginners.

WP-Rocket supplies you with useful caching features such as Page Caching, Browser Caching, Preload Cache, Sitemap Preloading, Static Files Compression, ... Besides, it's eCommerce friendly, Developer friendly, and compatible with Cloudflare. We have an article about how to configure WP-Rocket to maximize speed, you can refer to it here.

Highlight Features:

• Quick Setup
• Preload Cache
• Preload Sitemap
• Page Cache (HTML Cache)
• Browser Cache
• GZIP Compression
• Multilingual Compatibility
• Lazy Load
• CDN
• Developer Friendly
• eCommerce Friendly
• Cloudflare Compatibility

After using WP Rocket, my PageSpeed Score increased from F(48%) to A(98%).

Last Words

By comparison, WP Rocket worked best on my website. However, each plugin has its own pros and cons and the effectiveness can be different depending on each site. In our case, we use Litespeed Cache, WP Super Cache and WP Rocket for our websites. One of these three plugins will be chosen depending on a certain site.

So you should determine if the plugin features can meet your needs or not. Hopefully, one of these above plugins will be your desired one. In addition, don't forget to follow our upcoming posts to reach more useful WordPress techniques!

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The publication at Meta Box.