Using xml files for a web project.

I have used XML to store "website" data for 20+ years. I don't make it directly accessible, but instead have a controller/servlet which retrieves it on the server, from a not-public-facing location, and then I typically render it as HTML in some fashion. I started this practice back when servers weren't as capable, and running a databse engine alongside your web server was considered excessive resource consumption. I switched much of my work to RDBs 10 years ago, but am now switching back to XML & markdown for content, as I find it easier to edit.

I do have some apps which store XML documents as columns in an RDB, but the extra care, encoding & validation led me away from that practice. I even had a couple of apps which stored XHTML in an RDB column, and then carefully dished those for in-browser editing with redactor - not the safest practice.

As for lighter or faster, however you measure those, I was working at one point with a 20,000 "record" XML document, with no noticeable lag dishing pages based on processing that.