Yep LXQt is a beast, super snappy and complete. I use it on an old laptop (2012) and it still works great with a very low memory footprint (much lower than XFCE when I tested a bunch of them).

If I want something light, I tend to gravitate towards fluxbox, icewm, i3/sway, windowmaker or twm depending ony mood and the paradigm I am looking for.

There are many other options though.

LXQt is great, except for the fact it can only do 'regular, italic, bold, bold italic' for font weights even when a font supports medium (my preferred font weight, regular just seems so dainty now I've gotten used to medium).

I also like the fact that it allows use of any window manager and even supports Wayland now (so Wayfire is an option).