Optimizing Virtual Memory Performance

2010-03-07 updated 2010-04-21 • SEND FEEDBACK •
Related: How-To, memory, optimization, software

Pages out = BAD

When the Mac runs low on memory, it is forced to write and read the contents of the memory chips to disk, which is very, very slow. This is called virtual memory, and the write/read activity is called swapping, specifically the writes are called page-outs and reads are called page-ins.

You can see if your Mac is “paging” by opening Activity Monitor and viewing the System Memory Tab in the main window.

Virtual memory is very slow, so when it happens, your Mac will feel really sluggish. If possible obtain and install additional memory— that’s your best best.

Some Macs have limits on the amount of memory that can be installed, so your only option might be to install a faster hard drive, or better yet, a quality solid state drive such as the OWC Mercury Extreme.

Speedup — disabling “Secure virtual memory”

Applies only to older versions of OS X — forced on in later versions.

Since virtual memory writes to disk, in theory it could write memory containing passwords, etc. Later, a nefarious type could read unused blocks off disk, hoping to find such information.

But unless you work for the CIA or a drug kingpin, this probably is not at the top of your list of concerns. And if your Mac crashes, this is all for naught anyway, since it won’t know which pages to erase once it reboots. Anything needing that level of security should never go onto a laptop anyway (though irresponsible jackasses are happy to jeopardize your private information in more basic ways).

By turning off “Use Secure Virtual Memory”, performance can be significantly improved when low on memory, because the system won’t have to wipe blocks on disk to zero before and after using them.

Make sure that “Use secure virtual memory” is unchecked