01. Database Query Profiling
Slow SQL queries are the most common cause of high TTFB (Time to First Byte). Use tools like New Relic or blackfire.io to profile Magento controller executions.
Ensure custom collections utilize proper indexes and avoid loading full models inside loops. Instead, fetch specific attributes or use service contracts to fetch batch data.
02. Varnish Cache Tuning
Varnish is critical for caching static blocks and product pages. Verify that your Varnish TTL (Time to Live) values are configured correctly and that custom headers do not bypass the cache.
Leverage Edge Side Includes (ESI) to inject dynamic elements (like personalized greeting bars) into otherwise fully cached static pages, maintaining sub-100ms response times.
03. Redis Caching Configuration
Configure separate Redis instances for Magento's system cache and session storage. This prevents resource contention and ensures session reads/writes do not block backend API response times.
Tune Redis maxmemory-policy to volatile-lru, ensuring Magento can reclaim space from expired caches without dropping active user session data.
04. Content Delivery Network (CDN)
Route all static assets through a premium CDN (like Fastly or Cloudflare). Configure image optimization, CSS/JS compression, and Brotli compression at the edge to offload server processing.
CDNs can shield your origin servers by caching static blocks, query results, and media files, ensuring your store remains online during major sales events.