Safari beach ball Ventura (again)

Back in February I asked the community about a problem that I was having with Safari after upgrading to Ventura. Now, on 13.6.1, the issue is still present. That is, a random beach ball (temporary freezing) event that seems to come and go -- won't happen for a while and then might happen many times a day, and then won't happen for a while (but never quite goes away).

What appears to be happening is that for some web sites (not consistent), Safari is not releasing (purging, whatever) the associated Safari Web Content and Safari Web Content (Cached) processes when a tab or window is closed. I then open additional web pages, causing more such processes, and using more memory. Perhaps this behavior fills up the available app memory resulting in the beach ball? When the event occurs, I can see in Activity Monitor that (total) Memory Used has spiked to 11 or 12 GB (mostly App Memory), and lots of these Web Content and Web Cache processes taking lots (multi-GB) of memory.

I am mulling over upgrading to Sonoma 14.1.1 but wonder if the 2018 Mac mini is already memory stressed, maybe that won't help at all?

This is on a 2018 Mac mini 3.2 GHz i7, 16 GB, 1 TB SSD with two 2 TB HDDs. No Safari extensions; I have tried Safe Mode; I have tried the Develop -> Empty Caches (repeatedly) with no good results.