We have an Early 2008 Aluminium iMac. 2.4 GHz Core2 Duo, regular HDD. I think it came with 1 GB of DDR2 RAM but we upgraded to 2 GB. It originally came with Leopard but we upgraded to Snow Leopard on short order. So everything was good, maybe when it was brand new it would be ready to use in 25-30 seconds and after four years it would usually boot and be ready to use in 30-45 seconds. Pretty quick, maybe due in part to a hard drive that was mostly empty (don't know if that matters).
But then when Mountain Lion came out, I wanted to upgrade. I swapped out the 2GB of RAM for 4GB, ran the installation tool, and that was that. However, ever since then, boot time takes at least twice as long. (Both takes longer to get to desktop and takes longer for desktop to be ready for me to launch apps.) I knew it uses a little extra RAM but I didn't think it should be so bad for performance. I've reset PRAM and repaired permissions and all that boring stuff already, but it doesn't help.
I suspect there is just something that could be fixed so it doesn't take so long, like some caching setting or something (I really have no idea what I'm talking about) or that if I do a fresh install it should go back to booting in 30 seconds. However I don't want to spend half a day reinstalling and restoring on a hunch. So what are your suggestions?
I also plan on upgrading to OS X Mavericks in the fall as it seems like it includes performance improvements (not sure if it'll matter for boot though). Might upgrading to Mavericks "fix" some messed up setting that slows down boot time? Or would it not make any difference? Or would I have to do a fresh install when I upgrade to Mavericks to avoid a slow boot time? Or should I just wait till I want to upgrade and then do the whole fresh install and restore files/apps/settings from my time machine backup (or better to do manually)?
I'd like to add also that I have a MacBook Pro with an SSD and 4GB DDR3 RAM that came with Lion, and doing the same kind of upgrade process to ML as I did on the iMac didn't effect boot time on the MacBook Pro (it's still about 15 seconds).