If you're using Google Fonts service instead of self-hosting the fonts (even if they come from Google Fonts), Harry shows here the optimal performance and UX you can get with it, with lot of details, but a really simple solution.
There a lot of techniques combined here, but the resulting code is still slim and maintainable enough that it should’t pose a problem. The snippet doesn’t need breaking apart and can all be kept together in the
<head>of your document.
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