WordPress PHP SCSS Performance ACF Pro

Tushi WordPress Theme

How to build a WordPress theme from scratch with 98/100 performance

98/100
PageSpeed Score
0.8s
Avg LCP
40%
CSS size reduction
3x
Faster than parent theme

The challenge

The client had a commercial theme that barely reached 45/100 on PageSpeed. The site loaded 8 different plugins for features that could be native to the theme, and the CSS weighed 2.3MB unminified.

The approach

I chose a template parts architecture with pure PHP, zero page builder. Every feature normally delegated to plugins (custom metaboxes, gallery, contact forms) was implemented natively with ACF Pro or custom code.

The CSS system is built on custom properties, with a single compiled and minified SCSS file. I completely removed jQuery, replacing every dependency with vanilla JS.

The solution

The solution

The result is a theme that weighs 180KB total (CSS + JS), loads 0 unnecessary plugins, and reaches 98/100 PageSpeed on both mobile and desktop. The design system is based on CSS tokens that allow the client to customise colours and typography through a simple UI in theme options.

The problem: 45/100 PageSpeed

The initial audit revealed a series of classic problems: render-blocking resources, unoptimised images, unused CSS. The commercial theme loaded 14 different font weights. JavaScript was all synchronous in the <head>.

Architecture: template parts and hooks

I structured the theme with a granular template parts system. Each component (hero, card, form) has its own separate PHP file, included via get_template_part(). WordPress hooks allow components to be modified without touching the core.

CSS: from 2.3MB to 180KB

The original CSS had years of accumulation. I wrote a new system from scratch with SCSS, using custom variables for design tokens. Automatic tree-shaking during build eliminated all unused CSS. Result: 180KB total versus the original 2.3MB.

The result The result

The site went from 45/100 to 98/100 PageSpeed. Bounce rate decreased by 34%. Conversions increased by 22% in the first month.

Lessons learned

The most important lesson: WordPress plugins are a performance tax. Every plugin you eliminate is a win. Second: ACF Pro used well replaces dozens of plugins.

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