Hello, I know this post sounds like 2013. Mountain Lion 10.8.5 is still running on my iMac/3.5 i5/1t FD and is rock solid. But since the beginning, Safari has been the weakest link. Slow, slower, slowest. I am often suggested to upgrade to Yosemite but I'm terrified to do so since I still read numerous posts of users having problems with Wi-Fi, slow response from Finder, etc. My sister has a Core2Duo iMac 24 and runs Yosemite on it. She has no apparent problems but her iMac has become slower than my vintage Power PC Performa 6500 tower. I am willing to upgrade to Mavericks to have Safari 7 which is supposed to be snappy and without issues, but how can I do that. Applestore gives me the possibility to upgrade to Yosemite only. Where do I get Mavericks? Can I install Mavericks on a partition and dual boot my iMac in order to revert back to ML in any case. What if Mavericks is not as solid as ML on my iMac. I tend to stick to the OS that came with the computer I buy. I have only brand name apps like Intensify, Perfect Photo Suite, Lightroom, etc. Help and oints very welcome. Thanks in advance.