Blocking means, that the resource is waiting for a connection. Usually it happens when there are already too many connections to the server, and previous connections need to close first. The actual loading time of the asset is only 30.7 ms, which sounds about right.
The reason for the block can be different, it is up to the browser to decide which assets load first. I can imagine that it decides to load up other crucial asset items first, and not to bother with this font, until it is neccessary. I think in your case only the settings “tick” icons are rendered, which are not visible, so the browser probably decides to block that until neccessary.
If you test this on a real world browser, the results will be probably different on each one. This is not font awesome though, it is only a small subset of custom generated icons.
I do not recommend, but you can completely remove this from wp-content/plugins/ajax-search-pro/includes/classes/actions/class-asp-stylesheets.php file, lines 114-124. It will probably cause issues though.