Fishy URL extension

In Firefox address bar, the homepage URL of my Alter blog continues like this:

.altervista.org/?doing_wp_cron=1456045327.6362500190734863281250

But in Edge and Chrome, the URL seems OK; that is: .altervista.org/

Am I being compromised? Should I do anything? Or, is it the way with Firefox?

P.S. I wasn't logged in to my Dashboard.

It's completely normal, it happens when WordPress has to run a cron job. You don't have to worry about it (except if you read it on each page, and notice a seriously slow loading, but this is not the case).

Thank you Karl.