[v1.2.7] Free Download [Kirby] Font Awesome Manager - Xenforo
Font Awesome Manager Nulled does allow to automate the process of creating subsets.
XenForo uses the icoon font Font Awesome Pro 5 which contains a few thousand icons of which XenForo does usually only use a few hundred.
But as all icons are included in the CSS and font files, browsers have to download the full font files and CSS which does cause a significant overhead in most cases.