What label should I use to write small icons on the mobile phone page?

Using < I > as an icon is not semantically correct (although it looks like the abbreviation of icon);

& lt I> is shorter than < span >, but there is little difference after gzip, but you can press three keys less when typing;

Most icons are empty.

Generally speaking, I don't see any defects in practicality for the time being, so I don't need to use it.