I am pretty sure icons are easier and faster to recognize, except when you make them (too) small. In particular, they probably are easier in the long run, as long as they don't change position. But in a context where things change or you need a lot of buttons, words probably win.
This is not true. Just today for example, in android at least, I went to whatsapp, selected a chat with long tap, I want to archive the chat. I have a download like button. Apparently that is the archive button. I had no idea.
If it was the opening to the alternate dimension, I wouldn't still know. If it was something harmful like backup and delete, I wouldnt know. I just took the plunge and hoped it wasn't gonna be harmful. Luckily it was archive.
These kind of stupid things are there now in their calling screen and other places. Absolutely ridiculous and hard for me. Now imagine my parents who are 60+!!
You're wrong. There's a body of literature on this. I encourage you to review it.
This is why you need both. Icons are faster to recognize, but words tell you what the icons need. So you need the words at first to discover the icons, then the icons serve as valuable tools for scanning and quickly locating the click target that you are looking for.