Have you tried to update to Mavericks (OSX) as of yet ?

Following the smooth transition to IOS 7 on iPhone and iPad (although I'm still not necessarily convinced it's actually better than IOS6 as present) I downloaded and (attempted) to install the new Mac OS on my iMac and Macbook over the last few days.

On my iMac it was literally a nightmare. Firstly the update kept failing partway through download. I'm guessing this was an artefact of Apples update servers not being able to cope although I waited two full days before attempting the download. Finally managing to download the update the installing effectively bricked my computer. I was forced to start up 'Cmd R' from the safe disk partition following a hard reboot, even then the base operating system was only partially functional and when I final managed to get things working the software refused to install and I had to repair the hard drive in disk utilities before the install proceeded. From there it took another two hours to complete everything. I might 'review' the changes later but in terms of performance there is a definite dip in speed and I'm having to turn off and reboot the machine daily to get things performing at anything like 'normal' functionality. At the moment I wouldn't recommend moving from Mountain Lion to Mavericks until the .01 revisions to improve performance come through.

On the MacBook Air (an older machine in fact) things have been smoother and although it took some coaxing the hard drive (used for Time Machine Updates) resisted the update and I needed to move the back up files to enable it. Having done this, following some quick research on-line the update worked fine and the machine is actually working a little faster than under Mountain Lion. It did take some finessing to get the machine to update to the new version of Pages however (which incidentally I hate along with Numbers - too IOS with missing functionality as compared to the old OSX versions).

All in all I'd probably suggest giving Mavericks a miss unless like me you just like to be up to the minute !