Earlier plasmashell assumed that you'll get free space info immediately (which is not true in case of losing connection to server containing a mounted filesystem - statfs will wait for response forever and freeze everything since it's happening in main thread)
I moved obtaining that info into different thread so that case won't freeze anything anymore.
It creates exactly one thread per one path. If a path is already being processed, new thread won't be created.
Also I implemented a timer used to notify about broken connection after 15 seconds.