Every WordPress performance guide says the same things. Install a caching plugin. Optimize your images. Use a CDN. And most of it is correct. But it misses the part that actually matters for most sites I work on.
The real bottleneck is usually the theme
Most WordPress sites I audit have a theme that loads between 400KB and 1.2MB of CSS and JavaScript on every single page. Page builders are the worst offenders. Elementor loads its framework CSS, its widget CSS, its responsive CSS, and its frontend JS whether your page uses 3 widgets or 300.
You can install every caching plugin in the WordPress directory and your LCP is still going to be 3+ seconds if the browser has to download and parse a megabyte of CSS before it can render anything.
What I focus on
CSS weight. My themes ship between 25-40KB of CSS total. That’s not minified-and-gzipped-to-look-small. That’s actual file size. I write CSS by hand, I don’t use frameworks, and every line serves a purpose. If a page doesn’t use a style, that style doesn’t load.
JavaScript. Vanilla JS only. No jQuery (unless WordPress core forces it for admin features). No React bundles for a contact form. The main.js for most of my sites is under 8KB. Deferred, in the footer, non-blocking.
Image pipeline. WebP with AVIF fallback where supported. Proper srcset attributes. Lazy loading below the fold, eager loading for the hero. This alone usually cuts LCP by 40-60% on image-heavy sites.
Server response time. Object caching with Redis if available. Proper database indexing. Query optimization for custom post types. Most hosts give you tools for this but most developers never touch them.
The results
Every site I’ve built in the last year scores 95+ on Google PageSpeed Insights on both mobile and desktop. Not because I’m doing anything revolutionary. I’m just not loading things the page doesn’t need.
That’s really all performance optimization is. Stop loading things you don’t need. The tools are there. Most developers just never audit what their theme is actually sending to the browser.