Before we compare Redis and Memcached, let’s get honest: most WordPress sites asking this question don’t need either yet.
I see this at Rocket.net daily. Developers install Redis on shared hosting with 512MB RAM and wonder why their site crashes. Agencies set up Memcached clusters for static brochure sites that would be fine with just page caching.
This guide gives you a framework—not just a comparison. You’ll know if you need object caching, which to choose if you do, and when neither is actually the right answer.
First: Do You Actually Need Object Caching?
Object caching stores database query results in memory. Instead of asking MySQL “What’s the site title?” 50 times per page load, WordPress asks once and retrieves it from memory.
When object caching matters:
- Dynamic sites (WooCommerce, membership sites, forums)
- Logged-in traffic (page cache doesn’t help here)
- Complex queries (custom post types, meta-heavy sites)
- High-traffic admin (multiple editors working simultaneously)
When object caching is overkill:
- Static blogs (page cache handles this)
- Most brochure sites (same)
- Single-author sites (admin slowness is usually CPU, not database)
The test: Disable object caching temporarily. If you don’t feel the difference, you didn’t need it.
Redis vs Memcached: Head-to-Head
| Factor | Memcached | Redis |
|---|---|---|
| Speed | Slightly faster for simple key-value | Negligible difference in practice |
| Data Types | Strings only | Strings, lists, sets, hashes |
| Persistence | Ephemeral (memory only) | Optional persistence to disk |
| Memory Efficiency | Slightly better | Good |
| WordPress Integration | Drop-in file | Plugin or drop-in |
| Complexity | Simpler | More features, more to configure |
Here’s what that actually means for WordPress:
Data Types: Does It Matter?
Redis supports complex data structures (lists, sets, sorted sets). For WordPress object caching, this is mostly irrelevant—WordPress stores simple key-value pairs.
Persistence: Feature or Trap?
Redis can persist data to disk. Memcached loses everything on restart.
The trap: Redis persistence sounds like a safety feature. For WordPress object caching, it’s actually a performance risk. If Redis restarts and loads gigabytes of cache from disk, your site crawls until the cache rebuilds.
Memcached’s ephemerality is a feature, not a bug. Cache should be fast and disposable.
WordPress Integration
Memcached: The drop-in file is standard, maintained by WordPress core contributors, and Just Works on hosts that support it.
Redis: Requires the Redis Object Cache plugin or a custom drop-in. More setup, more options, more that can go wrong.
My Decision Framework
Choose Memcached If:
- Basic WordPress site, no WooCommerce
- Simple hosting environment
- You want the lowest-friction solution
- Your host offers it (cPanel usually has it)
Choose Redis If:
- WooCommerce or heavy dynamic content
- Multiple WordPress instances sharing cache
- You need cache analytics (Redis has better introspection)
Choose Neither If:
- Page cache is handling your traffic fine
- Database queries aren’t your bottleneck
- You’re on shared hosting with limited RAM
FAQ
Will object caching speed up my frontend?
Not directly. Page cache handles frontend speed. Object caching helps logged-in users and dynamic content.
Can I use both Redis and Memcached?
No—WordPress uses one object cache backend at a time.
Last updated: February 2026. I work at Rocket.net where we configure object caching automatically.
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