If you’re using Firefox with McAfee security product installed in your Computer and if you ‘re experiencing slow browsing in Firefox 10.0.1 – blame McAfee Site Advisor add-on installed for Firefox. As Mozilla recommends users to disable this add-on that increases memory consumption of Firefox and they’re planning to block-list current add-on version 3.4.1 and contacted McAfee about the same to fix.

Disable McAfee Site Advisor add-on as it has terrible Memory Leak

“If you have the McAfee Site Advisor add-on installed in your Firefox, I recommend you disable it immediately because it has an appalling memory leak. “ Nicholas Nethercote working on Memshrink project says.

Mozilla really needs to be aggressive against these add-ons as Mozilla  doing their best to get rid of Firefox performance and memory consumption issues with Memshrink project, these third-party add-ons letting them down and users.

“This morning I tested Site Advisor 3.4.1 myself, and found that, when enabled, it leaks every single content compartment that is created. In other words, most of the JavaScript memory used for any page opened with Firefox is never reclaimed.  In terms of memory consumption, this is pretty much the worst possible behavior for an add-on.  This excessive memory consumption is likely to cause Firefox to run much more slowly and crash much more often. “  Nethercote noted in Mozilla blog.

McAfee Site Advisor and ScriptScan older versions are also block-listed by Mozilla in the past due to crashing Firefox, now same is repeating here.  Mozilla not tested ScriptScan 14.4.1 though (current version) as it may comes after installing McAfee. It is  better for users to disable all McAfee add-ons installed for Firefox.

You can read this bug details here.