Every time someone visits your WordPress site, a remarkable amount of work happens behind the scenes. PHP code executes, database queries run, files get assembled, and finally, a complete HTML page gets sent to the browser.
This process might take 2-3 seconds. Do it thousands of times per day, and your server groans under the load.
Caching changes everything. Instead of rebuilding pages from scratch every time, caching stores ready-made versions. That 2-3 second generation becomes a 0.1 second file delivery. Your site feels instant, your server stays relaxed, and your visitors are happy.
Understanding How WordPress Works (Without Caching)
To appreciate caching, you need to understand what happens without it:
- Visitor requests a page — Browser asks for yoursite.ie/blog
- Web server receives request — Apache or Nginx accepts the connection
- PHP executes — WordPress core loads, plugins initialise, theme activates
- Database queries run — Content, settings, user data, options all retrieved
- Page assembles — Theme templates combine with content
- HTML generated — Final page output created
- Response sent — Complete HTML travels to visitor’s browser
For a typical WordPress page, steps 3-6 might involve 50-200 database queries and significant PHP processing. This happens for every single page view.
With caching, steps 3-6 are skipped for most requests. The pre-generated HTML is served directly.
Types of WordPress Caching
Page Caching
Page caching stores complete HTML pages. When a visitor requests a cached page, the server delivers the stored HTML without running WordPress at all.
Impact: The biggest performance improvement. Can reduce page generation time by 90% or more.
Best for: All WordPress sites, especially those with content that doesn’t change frequently.
Browser Caching
Browser caching tells visitors’ browsers to store certain files locally. When they return to your site, their browser loads images, CSS, and JavaScript from local storage instead of downloading again.
Impact: Dramatically faster repeat visits and page navigation.
Best for: All sites. This should always be enabled.
Object Caching
Object caching stores database query results in memory (RAM). When WordPress needs the same data again, it retrieves it from fast memory instead of querying the slower database.
Impact: Speeds up page generation for uncached pages. Essential for membership sites, WooCommerce, and dynamic content.
Best for: Sites with logged-in users, e-commerce, forums, and anything requiring frequent database access.
CDN Caching
Content Delivery Network caching stores copies of your static files on servers worldwide. Visitors download files from nearby servers rather than your origin server.
Impact: Faster global delivery, reduced server load, better handling of traffic spikes.
Best for: All sites, especially those with international visitors.
Page Caching Plugins Compared
WP Rocket
Pricing: From €59/year for one site Ease of use: Excellent — works brilliantly out of the box Features: Page caching, browser caching, lazy loading, database optimisation, CDN integration
WP Rocket is premium-only, but it’s worth it for the time saved. Configuration that takes hours with free plugins takes minutes with WP Rocket.
Recommended for: Businesses that value time and want reliable, hassle-free caching.
LiteSpeed Cache
Pricing: Free Ease of use: Good, but requires LiteSpeed server Features: Page caching, object caching, image optimisation, CDN, database optimisation
LiteSpeed Cache is exceptional — and free — but only works properly on LiteSpeed servers. If your host runs LiteSpeed (like SparkHost does), this is a top choice.
Recommended for: Sites hosted on LiteSpeed servers.
W3 Total Cache
Pricing: Free (Pro version available) Ease of use: Poor — overwhelming configuration options Features: Everything imaginable, including options you’ll never need
W3 Total Cache can do almost anything, but its complexity trips up many users. Misconfiguration causes more problems than it solves.
Recommended for: Technical users who want granular control.
WP Super Cache
Pricing: Free Ease of use: Good Features: Page caching, CDN support, preloading
WP Super Cache is simple and reliable. Made by Automattic (the WordPress company), it’s a solid choice for basic caching needs.
Recommended for: Those wanting simple, reliable page caching without complexity.
Cache Enabler
Pricing: Free Ease of use: Excellent Features: Page caching, WebP serving, minimal options
Cache Enabler does one thing well: page caching. It’s lightweight, fast to configure, and doesn’t bloat your admin.
Recommended for: Minimalists who want caching without extra features.
Object Caching: The Performance Secret
Page caching works wonderfully for anonymous visitors viewing the same content. But what about:
- Logged-in users (WordPress disables page caching by default)
- WooCommerce product pages with dynamic pricing
- Membership sites with personalised content
- Dynamic queries and filters
This is where object caching shines. By storing database queries in memory, WordPress works faster even when page caching can’t help.
Object Cache Options
Redis: The gold standard. Fast, reliable, supports clustering. Our recommendation.
Memcached: Similar to Redis, slightly simpler. Good, but Redis offers more features.
APCu: Local memory caching. Fast but doesn’t persist across server restarts.
Setting Up Redis
- Ensure Redis is available — Your host must have Redis installed
- Install Redis Object Cache plugin — From wordpress.org
- Enable the cache — Single click in the plugin settings
- Verify it’s working — Plugin shows connection status
SparkHost includes Redis on Starter plans and above, pre-configured and ready to use.
Browser Caching Configuration
Browser caching is controlled through HTTP headers telling browsers how long to keep files:
- Images: Cache for 1 year (they rarely change)
- CSS/JavaScript: Cache for 1 month to 1 year
- HTML: Cache briefly or not at all (content changes)
Most caching plugins configure this automatically. To verify it’s working:
- Visit GTmetrix.com
- Analyse your site
- Look for “Leverage browser caching” score
CDN Setup for WordPress
A CDN caches your static files on edge servers worldwide. For Irish visitors, files come from European servers. For American visitors, American servers.
Cloudflare (Recommended for Most)
Pricing: Free tier available, Pro from €20/month Setup: Change nameservers or use partial setup Benefits: CDN, DDoS protection, SSL, performance features
Cloudflare’s free tier includes CDN, basic DDoS protection, and performance improvements. It’s the obvious choice for most Irish businesses.
Setup steps:
- Create a Cloudflare account
- Add your domain
- Change nameservers at your registrar
- Configure caching rules in Cloudflare dashboard
BunnyCDN (Best Value)
Pricing: Pay-as-you-go, approximately €0.01/GB Setup: Plugin integration Benefits: Fast, affordable, easy to use
BunnyCDN is exceptional value and often faster than Cloudflare. Great for sites with international audiences.
Host-Integrated CDN
Many managed WordPress hosts include CDN. SparkHost includes Cloudflare integration on all plans, pre-configured for optimal performance.
Common Caching Mistakes
Caching Logged-In Users
By default, caching plugins exclude logged-in users — for good reason. Cached admin pages would be a disaster.
But some sites accidentally enable this, showing one user’s personalised content to another. Always test logged-in functionality after enabling caching.
Not Excluding WooCommerce Pages
Cart, checkout, and account pages must not be cached. Most caching plugins detect WooCommerce and exclude these automatically, but verify it’s configured correctly.
Forgetting to Clear Cache After Changes
Updated your homepage but still seeing the old version? The cache is serving the old page. Clear your cache after making content changes.
Better yet, configure your caching plugin to purge automatically when content updates.
Using Multiple Caching Plugins
Never run multiple page caching plugins simultaneously. They’ll conflict, causing errors, broken pages, and performance problems.
Choose one and commit.
Over-Aggressive Cache Expiry
Setting caches to expire after 10 minutes defeats the purpose. For most content, 12-24 hour expiry works well. Static pages can cache for weeks.
Measuring Your Caching Effectiveness
Before Caching
- Disable any existing caching
- Run a PageSpeed Insights test
- Test with GTmetrix
- Note the TTFB (Time To First Byte)
After Caching
- Enable and configure caching
- Let the cache warm up (visit key pages)
- Re-run the same tests
- Compare TTFB and overall load times
You should see:
- TTFB drop from 500-2000ms to under 200ms
- Full page load improve by 50% or more
- Server response times become consistent
The SparkHost Caching Stack
Every SparkHost plan includes:
- LiteSpeed server caching — Server-level page caching
- Redis object caching — Database query caching
- Cloudflare CDN — Global content delivery
- Browser caching — Properly configured headers
- Pre-configured LiteSpeed Cache plugin — Ready to use
We handle the technical configuration so you can focus on your business. Sites migrated to SparkHost typically see 2-5x performance improvements from caching alone. Our speed optimisation services include comprehensive caching configuration.
Take Action Today
- Audit your current caching — Is a caching plugin active and properly configured?
- Check for conflicts — Only one page caching plugin at a time
- Enable object caching — If your host supports Redis or Memcached
- Set up CDN — Cloudflare’s free tier is an easy win
- Test and measure — Compare before and after performance
Caching isn’t optional for a fast WordPress site. It’s fundamental. Get it right, and your site transforms from sluggish to snappy. For the full picture on site speed, see our complete WordPress speed guide and Core Web Vitals guide.