My #1 frustration as a Windows user is that every so often an applications or the whole system freezes up for a few seconds. I use MacOS sometimes and also Linux and I don't think either one is much better.
For instance when I launch a command prompt often it is up in <1s, but sometimes it takes 10s. That's a very simple program, but often there are security checks involved; even ssh logins to a linux server on a LAN have a long-tail distribution in time-to-prompt because maybe some daemon was swapped out.
I would be satisfied I had some visual indication that progress was happening (ALWAYS AND <100ms LATENCY) and some insight into the process (e.g. real progressbars... if hadoop can do it, why can't pandas?)
We don't want to trouble people with details, but what's the harm in telling the user we are waiting on a 30 second timeout?