One of the first things you should do after installing Manjaro is to update your mirror list, if you have recently installed your system with Manjaro you probably noticed right off the bat that when updating your system it takes a very long time and the downloads are quite slow going, finding the closest mirror can be an important part in your user experience, depending on your geographical location this may vary and of course your Internet connection plays a large role in how fast you communicate with these mirrors, finding the fastest mirror possible will help speed things up when your installing updates or installing new software on your system.
1.) Rating Mirrors.
Open up a terminal and using this simple command it will ping a list of mirrors from around the world, rating each one and reordering the list so the faster mirrors are at the top.
$ sudo pacman-mirrors -g
Using this command to update your sources and install any available updates.
$ sudo pacman -Syu