I know but what is causing this? I don't think Chrome just gives slower download speeds just because
Whatever site you are using to check is just faster on Edge. The days of Chome being top dog are long gone, it's actually a pretty dated system nowadays.
What about Mozzila firefox ? Is it better than Chrome and edge ?
Depends on the site. Each of the three have websites they are good and bad at. I'm personally a big fan of Firefox's extensibility, and while it's theoretically slower than Edge in some cases, it's right up there in terms of performance, outperforming the other two in some tests.