I use a M1 MacBook Air 2020 and run PhotoLab versions 5, 6 and 7 on three volumes, with macOS Monterey, Ventura and Sonoma respectively. The MBA being used as a test machine and frequent installs and uninstalls, each volume is fairly lean and clean nevertheless - and they all run smoothly too. I see no reason why, on your Mac, DPL should exhibit the issues you describe, except running DPL on an unsupported version of macOS.
How full is the start volume of your Mac? If there is enough free space, you could do the following:
- create a new volume with disk utility
- install macOS Monterey or Sonoma on that new volume
- when the installer asks for it: migrate data from the old volume…without Applications
- wait until you can log in to your account on the newly installed volume
- check your data, network connections etc.
Start installing apps one by one until you have what you really need.
Notes
- Why not Ventura? My production Mac is running Monterey and I plan to install Sonoma in a few weeks. I’ll not waste my time with installing an old OS over an even older one and I found Sonoma to be working smoothly, even its beta releases were fine.
- I used to be irritated by the changes Apple made to iTunes, but decided to move to “Music” and also started using “Apple Configurator 2” for mobile device management. I dropped a few legacy apps, the ones that were never updated by their respective developers…and usually found an alternative app that was supported.
- Sticking to old software obstinately is getting counter-productive after some time, but some of it can be kept alive on a separate volume or computer if you really must. Drop it, whenever you can, and get rid of the ballast!