I often see font icons that are done poorly. It's not a problem with the concept, but implementation:
* Irrelevant/meaningless characters used without textual label, which is total crap from accessibility perspective.
* Icons littering text copied to clipboard.
* Awful loading performance. Browsers optimize image loading very well: preload scanner, async loading, fetch priority, multithreaded decoding, but custom fonts almost always only start downloading after CSS is fetched, parsed and applied to the document (in order to avoid loading unused fonts), which delays loading by a network roundtrip + CSS processing time and either delays rendering or causes extra reflows.
I hate seeing 99%-loaded websites with hidden text so much that I've completely disabled support for Web Fonts in my mobile browser. That's a huge improvement overall, but makes font icons a collateral damage.
* Irrelevant/meaningless characters used without textual label, which is total crap from accessibility perspective.
* Icons littering text copied to clipboard.
* Awful loading performance. Browsers optimize image loading very well: preload scanner, async loading, fetch priority, multithreaded decoding, but custom fonts almost always only start downloading after CSS is fetched, parsed and applied to the document (in order to avoid loading unused fonts), which delays loading by a network roundtrip + CSS processing time and either delays rendering or causes extra reflows.
I hate seeing 99%-loaded websites with hidden text so much that I've completely disabled support for Web Fonts in my mobile browser. That's a huge improvement overall, but makes font icons a collateral damage.