Font awesome is causing the site speed issue on admin pages specially /admin/modules page.

We have experienced similar issues with FA previously, and in our case it was the pseudo elements detection from FA, which is a _HUGE_ performance killer. So zhis most likely is not a problem of this module directly, but of FontAwesome itself:

https://github.com/FortAwesome/Font-Awesome/issues/12994

(Sorry, incorrect closed as duplicate)

I'm having similar issues as well trying to maintain webforms a huge hassle as the build interface fails to load due to js running extremely slow. The issue lies with fontawesome being loaded through ajax.

Were you able to make any progress on a potential fix?

This appears to be caused by the settings shown in the image below.