Averting freezeups with outdated iMac OS that cannot be upgraded any more...

When uploading updates for PS (Beta), I get an alert from Adobe indicating there might be issues, unless I can upgrade to a more recent OS system, presently on a Mac OS within an iMac unit.  I just let it proceed, and it works well up to a point:

Most of the issue jobs bounce between PS, AI, and Acrobat, linking with MS Word for editing purposes.  They regularly freeze up if I leave too many files open once without saving then closing them.  When I do a 'save as' the use of memory quickly escalates on older OS systems and can freeze up if too many programs and files are open at once.

My current system has plenty of memory, unless I load it up with too many open files, or if I have to make edits and changes.  The artwork on it might take too many Gigs of Memory, automatically freezing it up, unless I limit the number of open files that can display, even after installing upgrades, now with 32GB RAM...  it too often seems to not be enough memory with the outdated OS.  

The other issue might still temporarilly be resolved - it seems to be less prevalent on the older system when limiting it to one or two files open in each program - especially when they take up anywhere from 500MGBs up to 2GBs each, seems to be stabilized unless major editing is necessary, running up memory too fast for ultra high definition to change/adjust images I need for present projects, where one image at 1.6GBS now compares to what we got 12 years ago for an hour of Adobe Premiere with final edits at 1080P HD size..