I'm using Krusader as a file manager, however it sometimes works too slow and that's why I'm looking for another one which is lighter and quicker. I like the rich functionality Krusader has and I'd like another one has it also.
Try GNOME Commander
GNOME Commander is a "two-pane" graphical file manager for the GNOME desktop environment. GNOME Commander aims to fulfill the demands of more advanced users who like to focus on file management, their work through special applications and running smart commands.
To install Gnome Commander, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:
sudo apt-get install gnome-commander