With the impending death of Windows XP updates and therefore increased vulnerability* I ordered a bunch of stuff to update the accounts PC to W8.1: the OS itself plus a hybrid hard drive to speed things up a little. But this isn't about that.
I also ordered a Crucial 240Gb SSD to upgrade the Macbook. Since running Mavericks things have been MUCH slower than they should be. Starting up is taking about twice as long as before to get a usable machine (the desktop image comes up, but nothing works at first) which isn't a big deal, but apps take much longer to both start and stop, and the whole system seems laggier than before with frequent appearances of the beachball. The memory upgrade might have made things a touch smoother, but no more than that.
So I'm undecided what to do. Revert to Mountain Lion with a fresh install: true 64 bit computing, apparently lower overhead. Install Mavericks from scratch: comes with extra cruft like maps, apparently sluggish and heavier memory use, but longer shelf life.
Actually shelf life doesn't really matter. This is a 5 YO computer, worth probably £300-£350 used with the various upgrades, and it only needs to last 1 more year before moving it on. Right now ML looks like an easy winner (there's nothing I've seen in mavericks that gives it any kind of extra functionality I would use) and it's the obvious candidate for the lower overhead it brings. When it comes time to sell then I can bung on Apple's latest & greatest OS (which everyone seems to run toward like lemmings) and let them deal with degraded performance issues.
The one thing I hope is that I can recover data and settings from Time Machine while stepping back. The present SSD will be 'archived' for a while just in case, but I don't want to move all applications over, and will be re-installing from scratch to try to get best performance.
*Chris, for the first time in years, opened a virus-loaded email the other day. It had been done really well, had all the bona fides, correct images, email addresses etc, and was relevant to some work she'd done. The give away was the attachment in the form of a '.zip' file and that didn't ring the same warning bells as it does in my head.
Avira free edition caught and appears to have stopped it.
For the first time ever I'm thinking about paying for anti-virus software as a 'thank you'.