I'm running 3.5.7 :1815bc54: (7202) on macOS 10.13.6
I installed 3.5.7 a few weeks ago and my distinct impression is how slow a complete refresh cycle has become compared with older Vienna releases.
Just to confirm my suspicions I've just timed the full refresh cycle for 312 items on a cold app start.
It took 3 mins 19 secs to retrieve 214 unread articles!
I've never timed this with older releases but I can tell you from having experienced the same procedure untold times with the same 312 items it was considerably faster. I would think it took significantly less than a minute.
A difference I've noticed is that where older releases seemed to refresh 'batches' of items (for want of a better word) the new 3.5.7 appears to take on all 312 items immediately, in a single go.
The spinners that appear next to items indicating that these are being accessed seem to tell me that. With older refresh cycles I saw Vienna 'step' through batches of, say, a dozen items at a time (again, based on how tha spinners next to the articles behaved). When a batch had been sucessfully finished, Vienna would show a new batch being accessed. This was repeated until all 312 items had been taken care of. Not a very helpful way of telling what I observed perhaps but distinctly different behaviour. What looked like a relay race now seems a mass start.
And long after incoming network data have stopped 3.5.7 is still busy for the larger part of those 3 mins 19 secs. Writing to the database? The Activity Window tells me '122 KB received'. Just to be clear: my subscription list hasn't changed for many months so I can compare how older Vienna releases compared to this new one.
Also: every once in a while, as I'm stepping through my unread articles using the Skip Folder button, Vienna chokes on some article: it's not shown immediately. I have to step back to another unrelated item feed and start again, just to bring that article up. The items Vienna chokes on are not data-heavy, e.g. having a large video embedded or some such. I would've been shown a 'spinning beachball'. Often it's just a short text item, completely innocent. And it's not choking on a particular feed. It's unpredictable and perplexing behaviour.
And, finally, this: viewtopic.php?f=18&t=27109 has still not been fixed, despite a promise in the release notes for 3.5.7 to the contrary.
All in all: Vienna still works but I'm much less satisfied than I was years ago when it operated flawlessly. But there's no going back: quite a number of feeds that older versions could no longer handle are now working again. The silver lining on a grey cloud ...