I am using PSE Organizer (on Windows) already many years and the number of photos is steadily growing. Currently 23.000 photo's / 80 Gb. I have just upgraded from version 10 to version 2020. Main reason for the upgrade is a hopefully better performance. In version 10 I experienced growing performance issues: regular screen freezes and sometimes a crash.
I was also wondering if there is something like a maximum size from performance perspective and if it is maybe better to make 2 smaller catalogs in stead of 1 big catalog. Although splitting up a catalog seems me not that easy and at least a lot of work.
Adobe has never published a maximum size for a catalog. I currently have a catalog that has 175K media files. I know of others exceeding 200,000. There have been many improvements in performance over the years. But there are also some newer drags on performance. For example, the changes made in Elements 11, I believe, created whole new type of tags. The media analysis that takes place automatically in Elements 2020 really eats up resources and can slow your computer to a snails pace while it is in progress. If you are able to do so, leave your computer running 24/7 until the initial analysis (Auto creations, smart tags and face recognition) is completed. If you need to work in the Editor and the media analysis is slowing things down too much, you can turn it off in the Organizer's Edit>Preferences>Media Analysis. Auto creations seem to take up the most resources.
It is not recommended to have multiple catalogs. And any benefit will likely be minimal. Enjoy all the new features that you will see in Elements 2020.
Thanks for sharing your experience Greg. Looking to your numbers I have still some room to grow. And indeed my (new) computer was working hard the past two days to do the face recognition and other analyses jobs which seems completed now. Performance is again good now
Periodically, Auto creations will kick in again to either replace creations that you have deleted or to change those in the Welcome Screen. I'm not sure what the schedule is for replacement. But if you see your CPU running in high gear the Elements Auto Creations 2020 process is likely the culprit. If you need to close it down, just end the process in Task Manager. It will automatically turn back on when you reboot or lauch the Organizer.