Al these issues with slow eBay, repeated signins, etc that are clustering here indicate a change somewhere.
None of these things are happening to me using Firefox (which would be indicative that it might not be a change on eBay's end)
Thinking there may be a common cause here (because of the clustering in time of these reports of weird problems), and I'd be inclined to point a finger at a browser, addon, or plugin update in the middle of the night, maybe an adblocker subscription update gone rogue and blocking a critical script, or an OS update (I don't do OS, addon, or browser updates and things pretty much always work for me).
One simple check would be to disable an adblocker before revising an item to see if the "slow ebay" issue disappears (probably unlikely but takes 10 seconds to perform and might rule that wild possibility out). If it did help with issues, next step would be to turn adblocker back on, but disable any rule subscriptions one by one to see which one it was.
The statements by some that no difference when multiple browser are tried shoots holes in some of that - but not the addon theory if, for example, users are using the same adblocker in multiple browsers..... hmmm .... A more likely common factor would be a Virus/malware suite update - like everyone with the issue is using Norton AV, and Norton pushed out an update 3 days ago for instance. That would like be browser agnostic and is a better explanation. Simple test, turn off AV and revise a listing where editing the description was slow before, or try to do one of the things that cause repeated sign ins, etc.
Just thinking out loud (can't help with specifics since, again, I have none of these problems)
