Lubuntu is a good operating system for many old computers, but not for all of them. Some computers have too little horsepower or memory. A rule of thumb is that the computer should not be more than 10 years old.
Memory (RAM)
For advanced internet services like Google+, YouTube, Google Drive, and Facebook, your computer needs at least 1 GB of RAM.
For local programs like LibreOffice and simple browsing habits, your computer needs at least 512 MB of RAM.
Processor (CPU)
The minimum specification for CPU is Pentium 4 or Pentium M or AMD K8. Older processors are too slow and the AMD K7 has problems with Flash video.
These are maintained by the Lubuntu team.
run dialog called from one desktop opens on the desktop with preferences dialog, regardless of which desktop is current (1445818).
All images require a DVD or USB. As a workaround, use the server or netboot images.
GTK warning about "The :insensitive pseudo-class is deprecated. Use :disabled instead." in Lubuntu 16.10 installer output (1633135).
Head over here to get it.
This release is supported until July of 2018.