Drupal Performance Optimization

Beyond raw query count, two related levers matter: maximize WARM (Dynamic Page Cache HIT) requests via render-cache keys + cache tags/contexts — the cold path is still common because authenticated routes are typically per-user DPC-cached — and watch for VariationCache conflicts (cache context consistency and "nothing in common" cache redirect warnings; see references/jsonapi-cache-context-consistency.md).

Measure the right thing FIRST (hard-won — read before profiling)

On the codebase these lessons come from, a whole audit went into xhprof + Lighthouse and moved the needle almost not at all. The single thing that did: cutting cold-render query count. Here is why the usual tools missed it, and what to measure instead.