I didn’t say it solved everything, I said when I ran it I got back to the same performance levels as a fresh boot. I had called Apple several times before this particular incident because of how poorly the system ran, but I had already typed a short story on an iPhone using my fat fingers and my internet speed problem wasn’t relevant to the actual article.
Since you seem interested, the ultimate problem behind my computers slow performance, which is still true today, was that I used the upgrade computer feature to copy files and programs from my old iMac to my new one. My old iMac was (actually is, it still works) a 2008. Although I had kept the OS up to date I hadn’t done the same with most programs, so moving them to my new machine was probably a mistake. Another recommendation by several Apple techs was on a major OS upgrade do a fresh install and not just a system upgrade. I hadn’t done that before because I didn’t know what programs I could potentially lose, since I hadn’t stayed current with them, and the easy path seemed to be just performing an upgrade.
Since my connection speed is now actually in the 10-15 mb range with the new OS release I may do the fresh install if that is still an option. I don’t remember that question in the last few new OS systems released but I’m not as nervous about trying now that I have a fairly reliable speed.
Migration Assistant slowed it down from previous OS clutter, I’ve gotcha. Often happens.
An Apple representative recommended “Dr. Cleaner” — no. I think you tried it and it seemingly sped up your machine. Could have disabled startup items for all we know and made a big difference.
The first post seemed to imply your brand-new Mac was running slowly and an Apple representative suggested a cleaning app which was a wonder cure. It now transpires it wasn’t a fresh OS and you tried the app off your own back which in your experience seemed to help.
You’ll appreciate why I found that disingenuous and people might get the wrong impression if they read your first post. I still maintain cleaner apps should be avoided unless you know what they’re doing and know what you’re doing.