How to optimize web fonts to prevent text rendering delays and layout shifts?

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Web fonts are an essential part of modern website design, but their improper loading often causes serious performance and user experience issues.

When a browser encounters the need to load an external font, it usually blocks text rendering on the screen until the font file is fully downloaded. This leads to the unpleasant effect of a blank screen or invisible text, where the user sees empty blocks in place of headings.

The second common problem is an unexpected layout shift at the moment when the custom font finally loads and replaces the default system font. The text changes its dimensions, causing neighboring blocks to shift, creating an annoying jittery page effect.

Modern optimization techniques are used to eliminate these problems.

1. Use the CSS font-display property with the swap value so that the browser immediately displays text using the system font and then replaces it with the custom one without delays.
2. Preload critical font files using the link rel="preload" tag in the page header section.
3. Carefully select fallback system fonts that are as close as possible in metrics to your primary custom fonts.

Additionally, it is recommended to convert font files into modern compact formats, such as woff2, which significantly reduces their size and speeds up network downloading.

How to optimize web fonts to prevent text rendering delays and layout shifts?

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