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Why Is Your Website Slow? It's Almost Always These 3 Things

No, you don't need a rewrite. Most slow pages share the same three problems: oversized images, fonts that block the text, and way too much JavaScript. Here is how I fix them.

2 min read

Performance work has a reputation for being complex, but most slow pages are slow for the same few reasons: images that are too large, fonts that block rendering, and more JavaScript than the page needs. Fixing those covers a surprising share of the gains.

Treat images as the biggest budget item

Images are usually the heaviest part of a page and often the Largest Contentful Paint element.

  • Serve modern formats like WebP or AVIF, sized for how they are displayed.

  • Always set width and height so the browser reserves space and avoids layout shift.

  • Lazy load images below the fold with loading="lazy", but never the hero image.

  • Give the main hero image a high fetch priority so it starts loading early.

Meme: a light, sharp hero image versus a 5.2 MB PNG shown at 400px

Load fonts without blocking the page

Custom fonts make a brand feel right, but they can delay text from appearing.

  • Self-host fonts and subset them to the characters you use.

  • Use font-display: swap so text renders immediately with a fallback.

  • Limit weights. Each weight is another file.

Ship less JavaScript

JavaScript is expensive because it has to be downloaded, parsed, and executed before the page can respond.

  • Render content as HTML on the server whenever possible.

  • Load heavy features, such as 3D scenes, charts, or editors, only when they are needed.

  • Check the bundle after adding a dependency. A small feature should not double the payload.

Meme: a landing page of three paragraphs and a button next to a huge JavaScript bundle

The fastest JavaScript is the JavaScript you never send.

Measure the right things

Core Web Vitals give a practical target:

  • LCP for how fast the main content appears.

  • CLS for how stable the layout stays while loading.

  • INP for how quickly the page responds to input.

Lab tools like Lighthouse are great for catching regressions during development. Real-user data from Google Search Console shows what visitors actually experience.

Make it a habit, not a project

Performance rarely fails in one big decision. It erodes through many small ones. Reviewing image sizes, font loading, and bundle size as part of every feature keeps a site fast without ever needing a rescue project.

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