I should've hesitated even longer.
The ~5000 item folder I tested just after upgrading to 14.7 did come up really quickly right after the upgrade. Today, after about five days of not testing, it's probably worse than at any time in the past. Of course, once I opened it once, it now opens very quickly. Just as before.
So, no better I'd say. Probably worse.
I probably could've hastened things up by clearing some caches as I did before. Then, this same folder would populate in a few seconds after the cleaning. Over time, probably after some other large folders get added to the cache it'd slow down again.
You'd think that a few lines of code, such as:
Has this folder been opened recently? If not, just open from scratch - never mind the cache.
would fix the problem. But, I guess this is why I don't work at Apple. I'd actually try to make stuff work, rather than tell whoppers about the reality and deny what's before everybody's eyes.
Wanna bet that by a month from now, this will get blamed on AI?