I just added "optional" libmenu-cache support to lxqt-panel and lxqt-runner.
Libmenu-cache is a mechanism used to cache the whole generated xdg application menu in lxde previously.
With this we can avoid parsing tons of the *.desktop files and xml files everytime to generate the app menu. We have a cached version of the menu and can load it instead. Once the desktop files are changes, the cache will be kept up-to-date, too. The cache is ugly, but it works well for years in lxde.
The change is optional. When menu-cache is abscent, all qtxdg things are just used as usual.

Besides, since libstatgrab is already used in many places of lxqt-panel and we have the dependency, I'd suggest that we replace libsysstat with it in plugin-sysstat too. Libsysstat and libstatgrab does nearly the same thing. Using libstatgrab directly is just as easy. So we can have less dependency.
What do you think, Kuzma?