Most WordPress caching plugins write pages to disk. That choice looks harmless until you need invalidation, cache variants, or a second server. Here is what changes when the page cache lives in Redis.
A speed test measures a few warm pages from your own desk. Your visitors get all the others. How to measure the one number that describes a cache honestly, the hit rate, and what quietly ruins it.
A page cache only makes the second visit fast; someone always pays for the first. What a cold cache costs, why the long tail never warms itself, and how event-driven preloading closes the gap.
A setup checklist for caching a WooCommerce shop with MilliCache: find your cache boundary, put each cookie on the right list, decide about the checkout and signed-in customers, and verify all of it.
Four things a WooCommerce shop can do with MilliCache, each backed by a check you run on your own store: shared pages for shoppers with a cart, a checkout cached on purpose, orders that clear their own pages, one rule for every currency.
Edit one synced pattern and the only safe move for most caching setups is flushing the entire cache. Why shared block content breaks URL-based invalidation, and how cache flags answer the question no database query can.