- It starts slower then Chromium.
- Right click and "Open in new private window" actually opens in a new private window. I prefer how Chromium does it, grouping all sites opened like this as tabs in one window.
- In Chromium, I can easily set any URL as a custom search engine with whatever parameters I like. In Firefox, I can't.
In my experience, Chromium renders and is interactive ~~faster~~ earlier, but they have about the same time between launch and browse. On Chromium, I launch, type in a site, hit enter, and wait and wait as it finishes actually starting up. FF takes longer to appear but is ready to browse as soon as it does. Or at least it did until some time in the last year or two, at which point it started taking a page out of Chromium's book. But honestly, I don't do cold starts that much so it doesn't bother me much one way or another.
https://addons.mozilla.org/en-US/android/addon/add-custom-se...
No, an extension shouldn't be necessary, but it works (I use it to search with searx).