Every page view on a WordPress site runs dozens of database queries — fetching settings, widget content, plugin options, menu structures, user data. Most of those queries return the same result they did a second ago, but the database has to re-run them anyway. Redis object caching solves this by keeping query results in memory, where they can be fetched in microseconds rather than milliseconds. On smartxhosting.uk, Redis is included free on every WordPress plan. This guide walks through what object caching is, how Redis fits into WordPress's caching stack, how to enable it via LiteSpeed Cache or the Redis Object Cache plugin, how to verify it is working, and what kind of performance improvement to expect.
What object caching is · How Redis works in WordPress · Redis vs page caching · Redis on smartxhosting.uk · Method 1 — via LiteSpeed Cache · Method 2 — via Redis Object Cache plugin · Verifying Redis is working · What Redis caches · Performance impact and when Redis helps most · Advanced tuning · Frequently asked questions
Every page load runs dozens of database queries. A typical WordPress home page might execute 30–100 queries just to assemble the page: fetch site settings, current theme options, widget content, active plugin configuration, menu items, recent posts, user sessions. On a busy site, identical queries run thousands of times per hour.
Object caching stores the results of those queries in memory. Next time WordPress needs the same piece of data, it reads from the cache instead of querying the database. Dramatically faster page loads, lighter database, more responsive site for visitors and administrators alike.
Without a persistent object cache, WordPress uses a built-in non-persistent cache that only lives for a single request. The cache is discarded when the page finishes loading; the next request starts from scratch. A persistent cache like Redis survives across requests.
Redis (REmote DIctionary Server) is an open-source, in-memory data store. Holds data entirely in RAM, so reads and writes happen in microseconds — orders of magnitude faster than any disk-based database.
Connected to WordPress via a plugin, Redis acts as a persistent object cache backend. Every query result WordPress would normally store in its non-persistent cache is saved to Redis instead, and served from memory on subsequent requests.
On smartxhosting.uk, Redis is backed by NVMe SSD for persistence — cached data survives server restarts without performance penalty. Combined with LiteSpeed Web Server and PHP OPcache, Redis completes a multi-layered caching architecture that minimises time between visitor click and page render.
Two different caching layers, both valuable, working together.
Stores the entire finished HTML page. When a visitor requests a cached page, the server delivers the HTML instantly without running PHP or querying the database at all. Fastest layer.
Works for anonymous visitors viewing published content. Cannot cache personalised pages (logged-in users, WooCommerce cart, dynamic content).
Stores individual database query results in memory. Helps on pages that cannot be fully page-cached — WordPress dashboard, WooCommerce cart and checkout, logged-in user pages, any dynamic content.
Reduces database load for page-cache misses.
Enable both. Page cache handles anonymous page views (the majority of traffic for most sites). Redis handles the pages page cache cannot serve. Between them, your site feels fast in every scenario.
Redis is available at no extra cost on every smartxhosting.uk WordPress plan — WP Minimum (GBP 2/mo), WP Standart (GBP 5/mo), WP Maximum (GBP 10/mo). Pre-installed on the server, ready to connect.
No separate service to request, no configuration to pay for. Just enable it in your WordPress caching plugin.
Recommended on smartxhosting.uk. Takes less than a minute.
127.0.0.1.6379.This is the preferred approach on smartxhosting.uk because LiteSpeed Cache covers page caching, object caching, browser caching, image optimisation and CSS/JS minification in one plugin. No need for a separate Redis plugin.
If you use a different page caching solution (WP Rocket, WP Super Cache) or prefer a dedicated plugin for Redis, use the Redis Object Cache plugin by Till Krüss. 1.5+ million active installations, lightweight, well maintained.
Do not enable object caching in both LiteSpeed Cache and Redis Object Cache simultaneously. Running both causes conflicts. Pick one.
LiteSpeed Cache > Cache > Object. Green status indicator next to the connection details confirms Redis is working.
Settings > Redis. Status panel shows Connected, cached keys count, hit/miss ratio, memory usage.
From Plesk's WordPress Toolkit WP-CLI:
wp redis status
Detailed connection info including Redis version, memory, uptime.
Free plugin that surfaces per-page query counts and cache hit rates. After enabling Redis, compare query counts before and after — typically 50–80% reduction.
After Redis is active, MySQL's slow query log and general query load should drop noticeably. Plesk > Databases > Tools & Settings > Database Server monitoring shows the decline.
Redis caches "objects" — WordPress's term for any chunk of data WordPress's caching API is asked to store. In practice:
wp_options table (site settings, plugin configuration).With Store Transients set to ON, expired transients no longer accumulate in the database — they live in Redis and expire cleanly. Reduces database bloat.
Measurable performance gains from enabling Redis typically look like:
Even on brochure sites, enabling Redis does no harm — it just does less good. On smartxhosting.uk where it is included, there is no reason not to enable.
360 seconds (6 minutes) is a sensible default. For sites with frequent content changes, reduce to 180 seconds. For static-content sites, extend to 3600 (1 hour).
Redis on smartxhosting.uk has a generous memory allocation per plan. Most sites use a few megabytes; WooCommerce shops with large catalogues may use 50–200 MB.
If Redis approaches its memory limit, it evicts old entries (LRU policy — least recently used). Heavy eviction means cache churn; bump up the object lifetime or the memory limit.
Persistent Connection ON means PHP reuses the TCP connection to Redis between requests rather than opening a fresh one each time. Small but real latency improvement.
On a WordPress multisite network, Redis caches per-site by default. Configure the object cache plugin for the network-wide mode if you have shared configuration.
Do I need Redis if I already have LiteSpeed Cache page caching?
Yes, for full-stack performance. Page cache handles anonymous visitors; Redis handles logged-in users, dashboard, WooCommerce, and any dynamic content page cache cannot serve. Enable both.
Will Redis slow down my site if something goes wrong?
Unlikely. If Redis is unreachable, WordPress falls back to its built-in non-persistent cache — the site stays up. Performance drops back to pre-Redis levels but nothing breaks.
How do I see cache hit rate?
Redis Object Cache plugin's Status page shows hit/miss ratio. Query Monitor plugin's panel shows it per-page. Over 90% hit rate is healthy.
Can I share one Redis instance across multiple WordPress sites?
Yes, with database separation. Use different Redis database numbers per site (db 0, 1, 2…) or use different key prefixes. LiteSpeed Cache and Redis Object Cache both support this.
What is the default Redis port?
6379 on smartxhosting.uk. Localhost-only (127.0.0.1) — Redis is not exposed externally for security reasons.
How do I flush the Redis cache?
LiteSpeed Cache: Cache > Object > Purge. Redis Object Cache plugin: Settings > Redis > Flush Cache. WP-CLI: wp cache flush.
Does Redis cache logged-in user sessions?
WordPress user sessions are stored in the database (with expiration). Redis caches them like other queries, so session lookups become fast. Actual session storage remains in the database.
Can I use Memcached instead of Redis?
Yes, both plugins support Memcached as an alternative object cache backend. Redis is more widely adopted and has better persistence; Memcached is leaner but has limits on data size per key. For most use cases, Redis is the recommended choice.
Why does my dashboard still feel slow after enabling Redis?
Dashboard speed depends partly on the browser rendering (many WordPress admin pages are JavaScript-heavy). Check that Cache WP-Admin is on in LiteSpeed Cache settings. Also ensure your PHP memory limit is adequate (256 MB+ is reasonable).
Is there any downside to Redis?
Complexity, mildly. Another service to understand, another cache to flush when debugging. But the performance benefit is real and the downside is small. Enable it on any WordPress site with non-trivial dynamic content.
Launch your WordPress site on smartxhosting.uk
UK hosting with the Plesk WordPress Toolkit, LiteSpeed Cache, Redis object caching, free Let’s Encrypt SSL, free CDN and daily backups — from £2/month.
View WordPress hosting plans →