Poor object caching configuration
- Caching
Problem Summary
Poor object caching configuration happens when Redis, Memcached, or another persistent object cache is installed but not sized, connected, or invalidated correctly.
Performance Impact
- Slow dynamic pages: Database results are not reused effectively
- Cache churn: Evictions reduce hit rate
- Stale data: Bad invalidation can show outdated content
- Backend pressure: Failed cache connections fall back to database work
How to Detect
- Object cache plugin diagnostics: Check status, hit rate, and errors
- Redis or Memcached metrics: Review memory, evictions, and connections
- Query Monitor: Compare database queries with cache enabled and disabled
Solutions
1. Use a Persistent Cache Backend
Redis is a common choice for WordPress object caching.
2. Allocate Enough Memory
Low memory causes frequent evictions and weak cache benefit.
3. Verify Drop-In Loading
Confirm wp-content/object-cache.php is active and connected.
4. Avoid Caching Broken Data
Exclude or fix plugins that store huge, volatile, or user-specific objects incorrectly.