For a while I’ve been very annoyed by how horribly slow Firefox is, writing it off as Firefox just having grown into a disgusting slow heap. That said, I wasn’t comfortable blaming Firefox in such an off-hand manner, the issue could be Ubuntu doing something wrong, or one of the extensions I use. I almost felt I’d confirmed it was Ubuntu a little while back when switching to the mozilla.org firefox install sped my Firefox up — yes it did (something to do with fonts and AA I’ve read) but it was still pretty slow. I’ve wiped my profile and rebuilt my Firefox setup from scratch a couple of times even, still all bad.

What I failed to do was start by blaming that which is, really, the most unreliable part of my configuration: the ten or so extensions I use. Extensions are outside the control of Firefox and Ubuntu, often written by some random, and often written badly. (Well, so I expect in my cynical way.) Today I nuked my Firefox install and browsed my usual morning sites with no extensions installed, using the Ubuntu Firefox, and it really is pretty snappy. I’ve now re-installed Google Browser Sync and browsing has not degraded. Over the next few days I’ll reinstall my set of usual extensions and find out which is to blame (if any single one).

My Firefox extensions are:

• Google Browser Sync (I don’t know how I lived without this. On the slowdown front it Seems OK, so far.)
• SwitchProxy Tool (Essential, I work through different redirected proxies throughout the day. Might be a better plugin for this though. There are notes on the addons.mozilla.org page that say this is a cause of slowdown.)
• AdBlock Plus (Difficult to live without this, I hate flashing/moving graphics all over websites. Flashblocker almost replaces it. Need flash+anigif blocker, that might be OK.)
• NeoDiggler (Provides the essential “clear URL bar” button, does some other things too that I don’t use.)
• Google Toolbar (I probably don’t really need this, it’s so common though that I doubt it is the problem.)
• Tab Mix Plus (Use this to tweak a few tab settings, can probably live without — closed tabs history is often helpful though.)
• Web Developer (Usually disabled anyway, very useful. It can cause slowness when enabled.)
• Firebug (Usually disabled anyway, extremely useful. It causes extreme slowness when some parts are enabled, shouldn’t be a worry in a disabled state though.)
• Google Gears (Have issues with this, it occasionally segfaults at shutdown-time, at least that’s where GDB points the finger. It is “Google BETA”. It makes offline Google Reader work, but I never use it.)

I’ll reinstall one per day over the next few days, in the order above, and see how my browsing joy fares. I’ll need at least a full day’s worth of browsing to work out if a plugin has a noticeable impact. (I don’t generally do a lot of web browsing.) I might try installing the Load Time Analyser extension next though, so long as it doesn’t slow anything down it seems likely to be useful.

Even with the massive no-extensions responsiveness boost, Firefox seems less speedy than Opera. I’ve been using Opera more often these days, now that it has some sort of sync feature it might be a viable Firefox replacement.