Ever since I installed Firefox 1.5 (and later 18.104.22.168) I have had nothing but grief. Freezes. CPU spikes usually in the 50s — which meant it took 20 seconds for anything to happen — but sometimes much higher, verging on 100%, which meant nothing happened however long I waited. Even if I didn’t get a CPU spike, going away from the machine with Firefox open in a window, even in the background, would make it freeze up, requiring that I use the task manager to kill it.
The problem was especially bad when I loaded a particular large and complex web page that I use several times a day (no, not this blog) — not only did it load slowly, but it would bring Firefox to its knees every time. And yet it worked fine in 1.07.
My first Google search suggested it was probably a plugin issue. I duly changed from Adblock to Adblock plus. I used less aggressive Adblock settlings. I replaced my tab manager with something that had a better reputation for playing nice with others. I removed this plugin, then that one. (See below for a list of what I’m running now — an only partly restored list from what I used to use.)
I disabled the prefetch. I turned off Bfcache — the caching of recently viewed pages — losing the lightening back and forth which was one of the best reasons to upgrade.
And of course I followed the directions at InternetWeek to play with settings in about.config to reduce the cache. And I carefully followed the directions as to what settings to use in place of the defaults for the about:config setting in browser.cache.memory.capacity.
But at last I can report that I think I have found the magic bullet: Ignore the directions in the cookbook about setting browser.cache.memory.capacity to 15000 if you have up to 1 Gig of RAM, or maybe 32768 if you have a full gig. I have a full gig of RAM, and it’s not shared with my graphics card, and my problem only went away when I shrank browser.cache.memory.capacity to the absurdly small 8192.
Here’s what I’m running at home at present in the way of extensions. I used to use Tab Mix Plus, and preferred its features to some what I’m using now, but it seemed to cause conflicts with some other plugins.
Enabled Extensions: 
- Adblock Filterset.G Updater 0.3.0.1 – Synchronizes Adblock with Filterset.G
- Adblock Plus 0.5.11.2 – Filters ads from web-pages. Now with whitelisting and synchronization.
- BugMeNot 1.3 – Bypass compulsory web registration with the context menu via www.bugmenot.com.
- ChatZilla 0.9.70 – A clean, easy to use and highly extensible Internet Relay Chat (IRC) client.
- Copernic Desktop Search Toolbar 22.214.171.1244 – Copernic Desktop Search Firefox Toolbar.
- EditCSS 0.3.5 – Stylesheet modifier in the Sidebar.
- IE View 1.2.7 – Open pages in IE via firefox menus
- Mozilla SpellCheck Libraries 126.96.36.199 – From the Mozilla Thunderbird 20050727 Nightly Win32 Build
- MR Tech Local Install 4.2.1 – Local Install power tools for all users.
- ScrapBook 0.18.5 – This extension helps you to save Web pages and easily manage collections.
- SessionSaver .2 0.2.1.031 – Magically restores your last browsing session.
- SpellBound 0.7.3 – Adds spell checker support to web forms and extensions.
- Tabbrowser Preferences 188.8.131.52 – Enhances control over some aspects of tabbed browsing.
- undoclosetab 20051204 – Adds Undo Close Tab.
- View Rendered Source Chart 1.5.02 – Creates a Colorful Chart of a Webpage’s Rendered Source
- Wayback 0.2.2 – Displays an archived version of the webpage.
- X-Ray 0.5 – See the tags on a page without viewing the sourcecode.
Installed Themes: