whaaaaat? My 2012 MacBook Air with 4 gigs of RAM and SSD is lightening fast. The thing that kills performance these days on Macs is if you still have a spinning platter of rust as your storage. Don't do that. (Aside: this is not surprising - Apple has spent a lot of effort optimizing the core OS for iOS, which has always been flash-only storage)
SSD longevity is not worth worrying about, and very nearly never was. Even with all the die shrinks reducing individual flash cell durability, consumer drives of moderate capacity still have write lifetimes exceeding a petabyte. Even a brutal workload of keeping the drive full and using it for lots of swapping won't wear it out before some other critical component of a 4GB machine fails. If you've got a very early and small SATA SSD you might be able to wear it out but the most likely mode of failure is going to be controller/firmware crashing, not NAND cell failure.
Still, if an OS cannot deal with me having a platter disk, it is SLOW (regarding file system access).
Windows is the same, slooooooow. Linux is seriously fast even with a HDD.
Of course, my next PC (whenever I'm gonna need one) will have an SSD, but that doesn't mean you shouldn't optimize "disk" access or filesystem speed in an OS.
