QuantumCache speeds up WordPress by caching database query results (not full pages). It integrates with WordPress query execution to cache post ID lists and content fragments that WordPress uses to build pages, reducing database load while preserving correct invalidation.

It is not an output buffer or page cache, and it does not replace existing page caching solutions.

Features

• Caches the results of the main front-end WP_Query for anonymous requests.
• Tag-based invalidation: purge by post ID, post type, or taxonomy.
• Fragment caching for the_content (classic) and core blocks such as core/post-content, core/latest-posts, core/archives, and core/navigation.
• Multiple storage modes:
  • Auto – use Redis if available, otherwise fall back to MySQL.
  • Redis – fastest mode; uses the PHP Redis extension.
  • MySQL – portable fallback using compact tables (qc_entries, qc_tagmap).
• Compatible with the Redis Object Cache drop-in.
• Avoids wp_options and postmeta storage – all cache data is stored in Redis or
  QuantumCache-owned database tables.
• Multisite-aware: per-site prefixes and per-site tables.

Performance summary

In local benchmarks, QuantumCache reduced database query execution by approximately 70–75% on cached pages and achieved cache hit rates above 95% when using Redis.

Under production-like load with a networked database, these reductions translated to roughly 20–40% higher throughput and 20–35% lower 95th-percentile response latency compared to baseline WordPress.

Actual results depend on theme, plugins, database topology, and traffic patterns.

Debug headers (optional)

Enable Settings → QuantumCache → Send X-QC debug headers to view cache status in HTTP responses:
* X-QC-Main: HIT | MISS | STORE
* X-QC-Store: AUTO | redis | mysql
* X-QC-Hydrated: number of posts loaded from cache

Append ?qc_nocache=1 to any URL to bypass caching for that request.

Debug headers are sent only when explicitly enabled in settings and contain no
personal or user-specific data.

Privacy

QuantumCache does not collect, send, or log personal data.
It stores cache entries in Redis or its own MySQL tables.
Other plugins on your site may handle cookies or data independently.
No remote requests are made, and no data is transmitted to external servers.