Diagnosing slow time-to-first-byte without blaming “images only”
Short answer: Slow TTFB usually points to server-side work—PHP, database, plugins, or upstream network—not to oversized hero images.
Owners often compress images repeatedly while the real bottleneck is a plugin query storm or undersized hosting for WooCommerce.
Quick isolation steps
- Test TTFB on a simple uncached URL vs homepage.
- Compare with a default theme briefly on staging—does TTFB drop sharply?
- Review slow query logs if your host provides them.
WordPress-specific suspects
Admin-ajax bursts, excessive cron, object cache misses, and synchronous remote API calls on every page load.
When to upgrade hosting
If CPU is pegged during normal traffic or the database disk is saturated, optimisation has limits.
Frequently asked questions
Does “page builders” affect TTFB?
They can—more PHP and database work per request. Measure before/after disabling heavy features on staging.
Are NZ data centres mandatory?
Not always—latency matters, but efficient application code often matters more than geography alone.