Mac OS X 10.8.5 is an unsupported version of OS X as of now, having received its last security update in the fall of 2015. Maybe you should consider to move on to another OS, considering that El Capitan is compatible with every Macs that was able to run Mountain Lion. Yes, on OS X 10.8.5 and Firefox 48.0.2 setting it to 0 cured the problem. Like SeaMonkey a bit high CPU for no good reason but it works. But on my other MacBook with macOS 10.13.3 and Firefox 58.0.1 it did not solve the problem. No change if using 0, 1 or the original 2. I also tried negative numbers as well, no change.
After a long beta period, Apple has released OS X Mountain Lion version 10.8.5, a system update for Mac users that delivers improvements to existing features and apps, as well as security fixes.
In a technical note over at its Support site, Apple says OS X Mountain Lion v10.8.5 Update is recommended for all users of OS X Mountain Lion, regardless of their current version.
The reason? “It improves the stability, compatibility, and security of your Mac,” Apple states.
In a detailed KB article, Apple elaborates on the contents of OS X Mountain Lion v10.8.5, describing the various fixes and tweaks included in the update.
For instance, an issue that may prevent Mail from displaying messages is now addressed, while AFP file transfer performance over 802.11ac Wi-Fi has been improved.
An issue reported by users would prevent a screen saver from starting automatically, and OS X 10.8.5 fixes that as well.
![Firefox for mac 10.6.8 Firefox for mac 10.6.8](https://cdn.macpaw.com/uploads/images/fix-firefox-problems-manually-clear-browser-junk.png)
The update further improves Xsan reliability, transferring large files over Ethernet, performance when authenticating to an Open Directory server, and “contains the improvements included in MacBook Air (Mid 2013) Software Update 1.0,” according to the Cupertino company.
An issue that prevented a smart card from unlocking preference panes in System Preferences is also patched in this new release of Mountain Lion.
The 10.8.5 update also packs the security patches deployed by Apple in Security Update 2013-004, a separate software update released this week for all Mac users.
Mozilla Firefox For Mac Os X
The security update deals with multiple vulnerabilities discovered in Apache, Bind, Certificate Trust Policy, ClamAV, CoreGraphics, ImageIO, Installer, IPSec, Kernel, Mobile Device Management, OpenSSL, PHP, PostgreSQL, Power Management, QuickTime, Screen Lock, and sudo.
Firefox For Mac 10.6.8
Apple adds a short note at the bottom of its security advisory, saying, “OS X Mountain Lion v10.8.5 also addresses an issue in which certain Unicode strings could cause applications to unexpectedly quit.”
Firefox For Mac Os X 10.7.5
Weighing in at 273.72 MB, the standalone OS X 10.8.5 update is available as a free download for all Mountain Lion users.