First, I killed Symantec Antivirus. Whatever version I was running was a pig -- 200 GB per day! Now down to 10 GB per day. I'm looking for a replacement that doesn't write all over my SSD over and over again.
I used Intego VirusBarrier for a while, but I got fed up with them as their updates never seemed to actually improve anything, just change what it looked like and get rid of features I used. A lot of their features are also implemented in a very strange way (NetBarrier for example is a total mess, and essentially useless), and every so often you'd get an update that required a restart, which is just annoying as a well designed app shouldn't require it.
So I decided to stop throwing money their way and have been using Avast! Antivirus for Mac instead; it's free, seems to do the trick and is very lightweight.
Personally I think it's overkill; the whole point of caches is to be able to reload data faster (less writes overall), so using a RAM disk means they'll be empty every time you restart, I've also found that RAM disks can get unmounted on sleep, and I've had others just unmount themselves seemingly at random.
I did used to use a RAM disk for /private/tmp, since for some reason OS X doesn't have a tmpfs equivalent, which I find kind of weird. You need to mount it with the union option which lets you set an existing directory as a target, that way the RAM disk takes over all subsequent writes, so it doesn't mess up your system.
But I stopped doing it as I don't think it was really making much of a difference personally. I do still use RAM disks for certain things though, such as macports' build folder as that's only needed temporarily and can be very write heavy when in use.
One optimisation I didn't see you mention was disabling access times for an SSD. Personally I do it for most volumes, as updating a timestamp for every file, every time it's opened, just isn't very useful in my experience, but it results in a ton of extra writes for no good reason. Granted they're not very big, but I haven't found a use case where I need it enabled, and you can generate a
lot of extra writes with access times enabled.
To disable it you need to run:
Replacing the slash for a path to a more specific volume if you prefer (in quotes if it has spaces). In my case I've set noatime on my root (startup) volume and my Time Machine volume.
Best thing to do is pop the command in a launch daemon and set it to start on mount. Personally I created a little script to run, so it'll only run the command if the target volume is mounted, and won't do anything if noatime is already set.
As to the original topic; I don't know if I'd disable journaling personally, as it helps prevent your file-system from getting into a corrupted state. Granted I'd prefer a file system that did copy-on-write instead, as it's more efficient and has other advantages as well, but Apple don't seem to be in a hurry to give us a new file-system.
