What is the most efficient and lightest web-based file browser similar to Filebrowser?

I am not sure I understand your requirements. What functionality of Filebrowser do you want to see? Read only or or read-write?

Firefox has (had?) FTP support, you could just run an FTP server and connect from your normal browser.

You could use autoindex built into your web server. That'll be the most lightweight option possible.

If these are not what you are looking for, we need details. Lots more details.

dufs?