For a few major releases now, Mac OS X has been fairly, uh, retentive about keeping inactive RAM around. Over time, it wouldn't be uncommon to see 4, 6 or even 10Gb of RAM labeled as inactive. Normally, this is a good thing, as the OS can access information in memory very quickly as opposed to accessing an HDD. However, there have been many instances where the amount of free RAM would go to zero, and there would be page outs/swapping even though there was RAM available in inactive form. Now, with 10.8.4, all of my Macs (I have 5 atm) all show very low amounts of inactive RAM usage - 20 Mb, 89 Mb, 112 Mb, 220 Mb and the "worst" is only at 660 Mb. Nothing has changed about my usage patterns. In fact, since I've noticed this, I've cranked up some activities that used to result in inactive RAM increases. Does anyone know if 10.8.4 had any VM fixes put in it? In any case, mark me as happy (so far). My frustration has been with not only the performance problems with respect to swapping, but also the many people here who dismissed this as a non-issue.