Firefox also sends enormous amounts of metadata about your browsing to the cloud and it's very difficult for non-savvy users to turn this off. They call it telemetry and 'safe browsing', but users overlook that every URL is checked against a database of URLs already in Google's 'safe browsing' repository. Firefox is not actually private and their business model can't allow for privacy, because they're in bed with Google.
Use something like Palemoon and configure about:config a bit more and you should be fine. But be very skeptical of Mozilla claiming FF is some privacy enhancing tool. Their plugins ecosystem is also a security nightmare...