The story
Tobi runs a staffing agency with about four hundred live roles. The site serves two audiences that want opposite things: employers reading a polished, static pitch, and candidates hammering a filtered search for “remote, contract, senior, posted this week”.
Page caching solved the first audience immediately and did nothing for the second, because every filter combination is a different query and none of them are a page you can pre-build. Listing pages stayed slow exactly where the candidates were.
The object cache is what fixed it: repeated taxonomy and meta queries answered from memory instead of the database, so filtered results come back fast even though they are generated live. The employer-facing pages are static; the search actually searches.