Firefox 57 shows import message in the Activity Stream. Mozilla has abandoned the plan of automatic data import from other browser on startup after Firefox browser’s install as they found performance issues with it, though they’ve fixed the those issues, but the silent migration process for some may result in slow and janky Firefox.
So at the moment, the company has no plans to ship automigration feature, instead, in Firefox 57, the browser will display a manual migration UI with a link in the activity stream, with a message, like this to import data from another browser: ‘Try Firefox with your favorite and bookmarks from another browser’.
Mozilla embeds import wizard in the activity Stream
Clicking ‘Import now’ will open the import wizard and allows user to choose import data and Settings from Edge or Internet Explorer or Chrome or Chrome Canary browser.
You should know about one significant change here: the import wizard dialog that showed up by Firefox 55 Streamlined stub installer in the last step will be removed from flow and appear in the activity stream on startup (after Firefox install). So the Mozilla has said bye to automigration feature, but now offers manual migration.
Firefox 56 : Mozilla replaces New Tab Page with Activity Stream