LXDE Forums

LXDE is considered lighter on resources than LXQt in its base state. This is primarily because LXDE is built using the older GTK 2 toolkit, which has fewer dependencies and a smaller memory footprint compared to Qt. PolyTrack

It's possible that newer versions of LXDE or its components might have addressed this, but given the age of that forum thread, it's also possible the issue persists in some configurations. that's not my neighbor