Lubuntu is Linux streamlined for older computers that have 512 meg of memory (I have 2 GB). It runs fewer processes and has less apps. It is a very thin OS which yet runs all the Linux apps.
I replaced the Mac Mini’s native OS from Apple when the Safari browser started choking up and freezing consistently. The Mac Mini would take a long time to load an app and if the app used too many resources it would crash. It also was starting to have problems when more than two apps would be running simultaneously.
The very first thing I noticed is that Chrome runs beautifully under Lubuntu and does not freeze on the Mac Mini. With Safari I could barely have two tabs open - I have no problems having six tabs open now under Chrome.
I couldn’t run the Tablo app at all previously but have no problems opening up the Tablo now on the Mac Mini.
No apps crash now at all. I can be playing music, editing a photo and downloading a file in parallel without any hiccups or lag.
A neighbor’s laptop had Windows XP and was crashing all the time. He couldn’t load Windows 7 because the laptop had limited resources. We put Lubuntu on it and voila he had a new laptop. Granted he doesn’t do any heavy lifting on it - just browsing the Internet and writing emails and documents. But it saved him having to buy a new laptop for a few additional years.
I can’t vouch for running heavy apps such as Plex but I have no problems editing and transforming MP4 files from Tablo with Avidemux or Handbrake on the Mac Mini under Lubuntu. I use the Java based Tablo exporters from this forum to run under Lubuntu.
There are other Linux variants that are similar to Lubuntu (e.g. Mint which is more polished but also uses more resources). I wanted the absolutely slimmest OS possible that had a GUI. I had originally gotten the Mac Mini so I could just do some iPhone programming. When that ended for me, I tried using it as a general purpose computer and two years later it started running out of steam… That’s when I started looking how to keep it going. It is also my main interface to my Raspberry Pi that I use as a media server.