When the available RAM becomes less than 1 GB, the OS kicks in its memory compression algorithms. When it does this, it uses a spare core for the compression. It will cause some slowdown of its own, but is faster than using swap. On quad core systems, this is not much of an issue, but on dual core systems, which many of you have, it can put a severe strain on the throughput of the CPU as once both cores are activated, the turbo speed is reduced in order to prevent overheating. This causes a twofold issue of memory being compressed while simultaneously lowering your CPU speed.
Many of you are also showing swap being actively used due to the file cache filling all of your RAM and the OS not releasing the file cache because Diablo 3 is still requesting use of that cache (it's the active application and the file cache is comprised mostly of D3 files). With the inability to compress this memory in an efficient manner (or at all), the OS then resorts to using swap, which is dog slow even on an SSD.
Now, because loading a new zone requires reading into RAM and your RAM is already full from both file cache and app memory, as well as the OS itself, it's almost a guarantee that you're hitting memory compression, swap, or both while you are loading the new zone. With all of that going on, it's like the good ol' days when virtual memory was a wee baby and if it kicked in, you had yourself a hell of a slowdown.
S4d1k, you could probably reproduce this issue if you pared down to 4 GB RAM or less, especially on a dual core machine. You might also consider taking a look at the following post and then utilizing the info in the post linked after it to test out the Mavericks VM system's settings to see if any of them allow for smoother gameplay:
Initial info post: http://us.battle.net/wow/en/forum/topic/11580908123?page=3#48
Details on the VM system settings:
Note to people posting in this thread: Do not attempt to use the information in the above two links. This is for testing purposes only by S4d1k and the QA team.
I strongly recommend revising the minimum system requirements to indicate that if you use Mavericks you need at least 6 GB RAM for optimal gameplay, preferrably 8 GB or more.
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