TL;DR: 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.
I wrote yesterday about a reader’s results with the McAfee Site Advisor 3.4.1 and McAfee ScriptScan 14.4.1 add-ons for Firefox — he was finding that they greatly increased Firefox’s memory consumption.
In the bug report I recommended that we block-list it immediately and contact McAfee, but Jorge Villalobos told me that block-listing is considered an option of last resort. Three McAfee people have been CC’d on the bug and I’ve been told that some other Mozilla people are contacting McAfee via other channels. Hopefully we’ll see concrete action soon.
If anyone else can replicate my results, particularly for older versions of Site Advisor, that would be useful to know. Steps to reproduce are in the bug report.
As for ScriptScan 14.4.1, I haven’t tried it myself because I haven’t been able to find where to download it from. My searching just turned up lots of references, such as this one, to when Mozilla block-listed version 14.4.0 because it was crashing so frequently. (Site Advisor 3.4.0 was block-listed at the same time. And SiteAdvisor 3.3.1 was also block-listed due to crashes!) If anyone can tell me where to get ScriptScan from that would be very helpful.
If you have any McAfee add-ons installed in your Firefox, I strongly recommending disabling them immediately. McAfee clearly has a poor record when it comes to the quality of their Firefox add-ons. I also personally found Site Advisor to be an extremely annoying and unhelpful add-on. I’m no expert on Windows security but if you are looking for alternatives I have heard numerous people say that Microsoft Security Essentials is the best anti-virus/security system for Windows — it’s reputedly very effective, and is free of charge and non-intrusive. It also doesn’t install any add-ons into Firefox.