Don't forget to reboot normally out of safe boot mode. Afterward, your Mac should not be running slower as a result of Safe Boot mode.
Booting into Safe Mode rebuilds the System Font and other caches. Catalina and Big Sur now place the System Font folder on a read-only partition, so you cannot just install fonts as in older macOS days. If you need to reinstall custom fonts, do so in your local (e.g. /Users/yourname/Library/Fonts ) folder, because it is the third location that the operating system automatically searches for fonts. Any valid font that you install there will also appear available in application font menus.