Improving performance with many fonts


I am developing a desktop app with Electron. I need to load and display many fonts (more then 500), at the same time. Currently I am experiencing big performance issues, when loading big amounts of fonts (I am using loading on scroll, fonts are .otf and .ttf, from local storage).

Is there a way to somehow improve the performance? I was thinking about unloading the fonts from the browser resources (is that even possible?) when they are not in sight. What else could improve performance? Maybe displaying them in a Canvas? Maybe encoding them somehow before loading? Any suggestions?