Yes, it will fix font-related CLS issues. The CLS issues happen because while your custom font is loading, it defaults to one that's already on your computer. Those fonts are usually pretty different styles/shapes/sizes/spacing, so once your actual font loads, the text on the visitors computer might grow, shrink, expand or shrink in number of lines. Things will shift, which is what Cumulative Layout Shift is all about. Here's an example of font layout shift: Use a web-safe font from the beginning and this will be avoided altogether.