It has always been rumored that Qt is bloated so programs written in Qt should be bloated. Some even argued that the LXDE developers made a wrong decision on the migration to LXQt.
Why not replace the assumptions with some experiments?
In fact, LXQt 0.11 even uses slightly less memory than XFCE (with gtk+ 2). After cold boot, LXQt uses 112 MB in the testing environment.

This is the testing setup:

1. Debian testing: Clean install in Virtualbox 5.1.6  (2016-10-02)
2. CPU: 2-core
3. RAM: 512 MB
4. Resolution: 1024 x 768
5. Desktop environments: LXQt 0.11, XFCE: 4.12.3, Cinnamon 3, Gnome 3.20

• Cold boot 1: After cold boot, I opened the application menu to make the icons loaded. Then, open an “xterm” window and get the result of `free -mh` command.
• Cold boot 2: same as 1, but it’s tested after installing Cinnamon and Gnome3, which bring some additional system services, so the memory usage after boot increased for all DEs.
• Open default FM: After cold boot, open the default file manager to browse the home directory. (For openbox, which brings no file manager, the gtk2 version of pcmanfm is used)

The memory usage of LXQt is quite similar to the original LXDE (gtk2) while many new features are added. Actually I used LXQt on my Raspberry Pi instead and it works flawlessly. It’s a pity that Rasbian does not ship with LXQt by default. 🙁

Next time, if others tell you Qt is bloated, and LXQt is not lightweight anymore, just direct them to this post.

To see is to believe:

LXQt 0.11

XFCE 4.12.3    

Cheers!