QuantumCache

QuantumCache accelerates WordPress by caching database query results and content fragments used to build pages. Instead of caching entire HTML pages, it reduces the database work required to render pages while preserving WordPress’s native invalidation behavior.

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.
• WP-CLI commands: wp quantumcache flush and wp quantumcache status.
• Metrics data layer: persistent hit, miss, store, and purge event counters available via Metrics::totals() and Metrics::deltas().

Performance summary

In benchmarks on a plugin-heavy WordPress site (WooCommerce + Yoast SEO), QuantumCache reduced per-request database queries by up to ~99% on cached pages and achieved cache hit rates exceeding 97% with Redis.

In the benchmark environment:

• Redis mode reduced warm TTFB by roughly 23–27% and total response time by 18–21% versus an uncached baseline.
• MySQL fallback mode delivered modest improvements (~3–10%) when Redis was unavailable.

Actual results depend on theme complexity, plugin load, database topology, and traffic patterns.

When to use QuantumCache

QuantumCache is useful when:

• Your site already uses a page cache (such as a CDN, reverse proxy, or caching plugin) but WordPress still performs significant database work.
• You want faster response times without relying solely on full-page caching.
• Your hosting environment supports Redis, or you want a portable MySQL fallback.

QuantumCache complements page caching rather than replacing it.

What QuantumCache does NOT do

QuantumCache is not a page cache or full HTML cache.

It does not replace solutions such as: * CDN caching * reverse proxy caches * traditional WordPress page caching plugins

Instead, QuantumCache reduces the database work required to build pages, making those systems more effective.

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.

WP-CLI commands

QuantumCache provides the following WP-CLI commands:

wp quantumcache status Shows the active backend, storage mode, and lifetime cache counters.

wp quantumcache flush Clears all cache entries for the current site.

Use –yes to skip the confirmation prompt.

QuantumCache Pro

QuantumCache Pro extends the core engine with advanced caching capabilities for WooCommerce and logged-in users.

See: https://quantumcache.io

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.