I recently upgraded to Mountain Lion (thanks to my developer account). I can’t really say too much about it thanks to the Non-Disclosure Agreement (yes, you’ve read lots of stuff from people who don’t care if they violate it, but I care). But I will say I’m happy with it as my day-to-day OS, but it’s not without some minor (to me, anyway) issues.
One thing I did notice was that my system seemed to be rather slow when bringing up a Save or Open dialogue. Now keep in mind that this is my home desktop Mac Pro – so it has 11 physical disk drives attached. I used to have this problem in the past, but I got rid of it by changing a setting in Energy Saver preferences – specifically, I unchecked “Put hard disks to sleep when possible.”
Why would I do that? Well, most of those disks would go to sleep – and whenever I’d go to open a file (using an “Open” command in a program) or save one with a dialogue, it would take a minute or so for all the drives to spin up. It finally got to the point where it started to grate on me, so now I leave the drives spinning. It hasn’t seemed to make a difference in my drives’ life – although, of course, I have no way of knowing for sure without entering an alternate universe and seeing how they fared there. But I’m not replacing them any more often than before.
So there’s a pair of tips here – if you have a lot of drives attached, and are seeing the same annoying slowdowns I was, uncheck the box and make your life easier. The other tip is after an OS upgrade, to check and see if any of your preferences failed to migrate over. I haven’t noticed any other ones yet.