Fonts not validating
Due to the fact that so many websites already use Google Fonts, it could very well be that the user already has the font in their browser’s cache.
If you use a more unique, premium font, it could actually increase download times.
Having fewer dependencies on your Word Press site is always better.
By using local fonts you have full control over the caching of your font files.
By hosting your fonts locally, or on your CDN, you can take advantage of a single HTTP/2 connection for better parallelism and multiplexing.
When you host fonts locally, you don’t have to rely on 3rd party services or their servers.
Services such as Typekit have been known to go down, which then, in turn, makes you look bad.
If you aren’t familiar with fonts you no longer need to serve all the font formats, you only need WOFF and WOFF2 (if you are going for extra compression).
With Google Fonts you also have one extra DNS request to lookup fonts.to grab the CSS file.