In this episode of Within WordPress, we feature Christos, a performance engineer at Presidium. Join us as we explore the intricate details of WordPress caching. From backend layers like Redis and Varnish to the front-end optimizations using plugins such as WP Rocket, we cover it all. Learn about the challenges and strategies for achieving optimal performance in WordPress websites, including handling logged-in users, capacity planning, and more. Whether you're a developer or a site owner, this episode is packed with insights to help you fine-tune your WordPress site's speed and reliability. 00:00 Introduction and Welcome00:42 Christos' Background and Early Career01:23 Getting Serious with WordPress03:06 Performance Engineering at Presidium03:54 Load Testing and Capacity Planning04:28 Understanding K6 and Protocol-Based Testing05:17 Challenges in Performance Metrics07:50 Real User Behavior and Testing09:32 Caching Strategies and Issues17:49 Advanced Caching Techniques21:35 Varnish vs. Cloudflare28:43 Redis and Object Caching36:16 Cache Invalidation and Browser Caching40:22 Understanding Static Sites and Caching40:55 Challenges with Long-Term Caching41:46 Performance Optimization Insights42:33 Plugin Warnings and Best Practices43:27 Caching Solutions and Preferences44:48 Advanced Caching Techniques46:15 Client-Specific Performance Strategies48:50 The Role of CDNs in Performance54:10 Fragment Caching and Collaboration57:21 Final Thoughts on Performance Optimization