Firefox 3 Performance Gets a Boost 550
jason writes "Mozilla has been working hard at making Firefox 3 faster than its predecessor, and it looks like they might be succeeding. They've recently added some significant JavaScript performance improvements that beat out all of the competition, including Opera 9.5 Beta. And it comes out to be about ten times faster than Internet Explorer 7! Things are really starting to fall into place for Firefox 3 Beta 4 which should be available in the next week or two."
Safari (Score:4, Informative)
Comment removed (Score:4, Funny)
Re:Safari (Score:5, Funny)
Re:Safari (Score:5, Funny)
Re: (Score:3, Informative)
Re:Safari (Score:5, Informative)
Re: (Score:3, Informative)
Re:Safari (Score:5, Insightful)
1. instrumented firefox (PGO technology)
2. ran the stinking benchmark with the instrumented code
3. used the feedback from the benchmark to automatically compile an optimized version of firefox optimized specifically for the benchmark.
4. Publish results of said benchmark for all to oooh and awwww over.
Isn't this as pathetic and useless as vendors manually tweaking their 3D drivers to artifically raise performance figures displayed in 3dmark? Did I totally misread TFA?
Re:Safari (Score:5, Interesting)
Re: (Score:3, Funny)
Re: (Score:3, Insightful)
There will still be a thriving market for LIVE music and plays and such things. Notice how the music industry never managed to die like it has always said it would? Started with the printing press, which is little different than me ripping a song off a CD, and now with the digitization of music and the internet. Both produced a cheap, easily duplicated copy without any harm to the original.
The only ar
Re:Safari (Score:5, Insightful)
* Copyists, who dealt with basic production and correspondence
* Calligraphers, who dealt in fine book production
* Correctors, who collated and compared a finished book with the manuscript from which it had been produced
* Rubricators, who painted in the red letters
* Illuminators, who painted illustrations
Ohhhh wait, people still write books and the industry didn't collapse. It just changed. I'm sure in 50years we'll be saying 'wtf was a publisher again?'. And nothing of value will be lost. Artists have the HUGE opportunity of being able to cut out the middle men (there are lots of them) with current technology. With less hands in their pockets they will make big money from live shows and bigger profit from merchandise as well as profits from ad supported downloads and site page views. Artists will NOT starve, i don't see how cutting away the massive corporations which artists are carrying on their back atm will hurt the artists.
Re:Safari (Score:5, Informative)
Re:Safari (Score:5, Interesting)
Re:Safari (Score:4, Informative)
Firefox 3 beta 3 on Linux is great (Score:5, Informative)
- Where as before FF2 would use around 500 meg it now only uses around 50 meg
- Flash no longer crashes the browser
- Javascript no longer crashes the browser
- Those long pauses as it is doing something that stalls the browsers operation are gone.
I couldn't believe the difference.
Re:Firefox 3 beta 3 on Linux is great (Score:4, Interesting)
I'm having terrible trouble with it. Bizarre image rendering issues (some render too high in their "frame", leaving a big black space at the bottom and the bottom half of the image rendered in the top half of the "frame", with the top of the image cut off, and other times images from WAY back in my browsing session will show up in odd places, like as a tiled background on another page), GMail hangs when I try to send e-mail every single time I try, and leaving it open too long has proven to be a great way to end up with an unstable mess.
Not refuting your post, just saying to anyone thinking about trying it, don't count on it being a great experience
Re:Firefox 3 beta 3 on Linux is great (Score:5, Informative)
- Ctrl-MouseWheel zooming scales the images as well so the pages look normal without text overlapping the graphics
That feature alone is worth upgrading for.
Re: (Score:3, Informative)
Re:Safari (Score:5, Interesting)
How about testing with a WebKit nightly?
Why is this marked as troll? (Score:5, Informative)
Re: (Score:3, Funny)
Because there are too many knee-jerk idiot mods who don't consider context and can't be bothered to check facts.
At least when they mod me "Offtopic" they'll have done the job correctly.
Re:Safari (Score:5, Interesting)
Safari 3.0.4: 10758.4ms +/- 0.5%
WebKi r30628: 3390.0ms +/- 0.3%
If the performance gain percentage is comparable on their test machine (big if, granted) the comparable time would be 5675.8 ms, 22% faster than the PGO Firefox build.
Re:Safari (Score:5, Informative)
1. Firefox 3 Nightly (PGO Optimized): 7263.8ms
2. Firefox 3 Nightly (02/25/2008 build): 8219.4ms
3. Opera 9.5.9807 Beta: 10824.0ms
4. Firefox 3 Beta 3: 16080.6ms
5. Safari 3.0.4 Beta: 18012.6ms
6. Firefox 2.0.0.12: 29376.4ms
7. Internet Explorer 7: 72375.0ms
The results are generated by using the Sunspider JS benchmark suite.
This looks great, but everyone should notice a couple of things that may not be obvious.
1) Sunspider JS benchmark is designed by Apple developers and they use it to show the world how much faster Safari is, however Opera seems to outpace the Safari developers even with their own tests. However, yes some of the benchmarks used are 'picked' to favor Safari, and some are 'extended' to hurt IE.
2) Sunspider over does the tests of the Append String performance problem to make IE look worse than it really is. IE's JScript is coded as JScript was designed, and because of this, it doesn't optimize string append operations by using newer code. So by using this text extra, it artificially make IE look horribly slow. IE8 and possible additional IE7 releases are spending time optimizing the base JSCript code from the original implementations/specifications.
http://blogs.msdn.com/jscript/archive/2007/10/17/performance-issues-with-string-concatenation-in-jscript.aspx [msdn.com]
3) If you remove the 'string' routine from the test, IE7, consistently outperforms Firefox 2.0, and is very close to even Safari for with the results were cherry picked.
http://www.codinghorror.com/blog/archives/001023.html [codinghorror.com]
4) Some of the numbers are quite questionable as to the validity. For example IE7 is given 72375 in this article, and yet the slowest machine our tech lab has ever benchmarked is 2x the speed, and this is on a very old AMD 1ghz machine that barely runs Vista in which the test yeilded the horrible results. So where did they get the 72375 number from? A Pentium 200?
Again reference this link so see that even this person's results are no where near the 75K ms time reported for IE.
http://www.codinghorror.com/blog/archives/001023.html [codinghorror.com]
So it is quite questionable and inaccurate to try to portray IE7 as 10x slower, when without the 'emphasized' string append slowdown in IE7, it is faster than FireFox 2.0 and within a few 'ms' of even Safari and the new FireFox 3.0 results.
Good job to the FireFox team, btw.. Also does anyone have benchmarks of the new FireFox using a non-Apple test suite?
Re:Safari (Score:5, Interesting)
While new features can be nice, I couldn't name a feasible feature that a significant number of people would want and it's not in core Firefox or in an extension already. What I want from Firefox now is to provide the existing features in a secure, stable, fast and memory conserving way, in this order. Heck, I've turned off most of the new features in Firefox 2.x and wished they'd fix some annoying bugs instead. In 3.x the developers did a lot of work to remedy a lot of those bugs and issues, so big big kudos for them!
Cleaner code matters - it results in less bugs and security vulnerabilities, easier to add features and most likely better code.
Re:Safari (Score:4, Insightful)
There are plenty of attacks (such as CSRF or XSS) for which your AV software and a firewall are useless against. You say security isn't a concern now, until you fall victim to one of these attacks that can only be thwarted by proper security in the browser.
Re:Safari (Score:5, Insightful)
Re:Safari (Score:5, Informative)
Re:Safari (Score:5, Insightful)
Extensions definitely should not have direct access to the threads. It would be an absolutely terrible idea. In fact, extensions shouldn't even know that there's multithreading going on behind the scenes. At best, extensions would be able to indirectly spawn threads and manipulate the spawned threads in a roundabout manner through that context using a thread-safe API.
Re: (Score:3, Insightful)
It's been my experience that the extensions and multiple open tabs cause bloat, not Firefox itself.
Re: (Score:3, Informative)
However, as one of the other replies mentions, it is partly down to the caching, which has now been adjusted.
If you are in the "I would rather have a slow browser with no cache" crowd, you can actually tune the cache down in the prefs.
Re:Safari (Score:5, Insightful)
-Aaron
Re: (Score:3, Interesting)
Re:Safari (Score:5, Informative)
Re: (Score:3, Informative)
That is not correct, maybe you are thinking of Thread Local Storage. All threads share the same address space and memory allocations (memory management techniques used inside the application aside). Perhaps this page (found with a quick Google search) should clear up the confusion: http://virtualthreads.blogspot.com/2006/02/understanding-memory-usage-on-linux.html [blogspot.com]
It is more a matter that tools such as ps report the VSZ (Virtual Set size) and RSS (Resident Set Size) -- basically this is the amount of mem
Re: (Score:3, Interesting)
Re:Safari (Score:5, Funny)
Re:Safari (Score:5, Informative)
Example: I have 8 gb in this system. Right now I only have FF and Thunderbird running (+ a few background processes). Current "commit charge" is 475mb, of which Firefox is using 150mb. The system says I'm using 280mb of swap, but it's not actually thrashing the swap disk at all. That swap space is reserved, presumably because it represents 280mb of idle memory that is eligible to swap out, should another process need it.
Windows allocates virtual memory quite aggressively (when properly coded). If a process requests 500mb, but only really uses 100mb of it, the remaining 400mb will be "allocated" to swap while the real memory remains available to other processes. The moment a memory page is accessed, it is marked "dirty" and moved to real memory.
It's very much like sparse files, where unused or 0-filled pages don't take up any physical space (except for the map entry). That's how virtual memory is supposed to work, and it lets developers simplify their code by not having to worry too much about the physical arrangement of memory. It's also partly why you should never run a system without a swap file, even if it has tons of memory. I've probably never used all 8 gb in my system, but I still keep a (small) swap file. If I didn't, and that process allocates 500mb, Windows needs to dedicate 500mb whether or not it is actually in use. It reminds me of real-estate players, who can "buy" million-dollar buildings with a relatively small amount of capital, the rest on credit. Swap is like a line of credit for the OS.
Linux probably does the same thing, but I'm not as knowledgeable about its inner workings.
Re:Safari (Score:5, Informative)
Okay, I ran it on OS X anyway. I'm too lazy to run it on Windows too :) Here are the results [slashdot.org]. The new version of Webkit/Safari does beat the nightly of Firefox, but it is close and they're both a lot better than any regular release.
IE7 is just slow anyway (Score:4, Informative)
Re:IE7 is just slow anyway (Score:4, Interesting)
There are a bunch of great reasons to use Firefox - adblock, keyword bookmarks, decent standards support, Firebug, etc. But in my experience (especially post-1.5), the responsiveness of the UI is not one of those reasons.
Re: (Score:3, Interesting)
Re:IE7 is just slow anyway (Score:5, Funny)
*For older versions of IE, 3 equals 1.
I tried Firefox 3 today (Score:5, Informative)
Heads up for all those trying Firefox 3 is Oldbar [google.co.uk]. I suggest you get it if you don't like the new 'innovations' by Mozilla Corp.
Re:I tried Firefox 3 today (Score:5, Informative)
Re:I tried Firefox 3 today (Score:5, Insightful)
The learn-as-you-go menu behaviour which they copied from Windows didn't work well in Windows either. The main problem is that it causes inconsistent behaviour. Repeating something doesn't necessarily give you the same menu items. It's good for newbies who read every single line before choosing one of them, but it's very bad for people who memorize what they do so they can repeat it quickly without even looking.
Re:I tried Firefox 3 today (Score:4, Insightful)
It's the KISS principle [wikipedia.org]. I'd rather have stupid software that works in a clear manner than all this crap that tries to figure out what I maybe might be wanting.
Re:I tried Firefox 3 today (Score:5, Insightful)
In which case you don't want the browser to autocomplete the URL for you at all, and the fact that it finds seemingly irrelevant matches shouldn't matter.
Re:I tried Firefox 3 today (Score:4, Insightful)
It does. Your "just fucking works" is slightly different from my "just fucking works", so it learns how we each work and adapts accordingly. It not only learns your habits in entering URLs in the address bar, but it also learns from your browsing history and bookmark use. When I type "sl" lo and behold, Slashdot is the first entry. When I type "gl" the first entry is for my Globe And Mail portfolio listing, when I type "bm" my online banking page comes up #1. Now, if I wanted to view other pages that I select often I can scroll further down, but in general all I need is two letters, down, enter and I'm at the page I want based on my own browsing habits. Now, your online banking might start with "sc" or "ba" or any other combination so you wouldn't want "bm" associated with that. Maybe "bm" links to your social networking site or something else you want. Why bother with one-size-fits-all when you can have custom tailored for the same price?
Re: (Score:3, Informative)
I've also got huge problems with image rendering (images that I brows
Re: (Score:3, Insightful)
When FF2 came out I didn't like the close buttons on the tabs, or the way that they were curved and didn't fit in with Windows' tabs, I didn't like the bland new icons, and it all seemed like a bunch of hype.
Of course now I like FF2, I like how the icons are less colorful and draw less attention, and FF3 seems like the scary new release threatening to ruin something that was perfectly good before.
Same goes for new releases o
Re:I tried Firefox 3 today (Score:5, Interesting)
Best of all, if I visit any site and then want to get back to that site again sometime, all I need to remember is something in the title or url of the page I was at.
Re:I tried Firefox 3 today (Score:5, Insightful)
Say you visited the Wikipedia page on the Tunguska event a couple of weeks. If you want to revisit the page, all you do is start typing the first few letters of "Tunguska" and the page comes to the top of the list. With the old type of address bar, you'll have to type the whole Wikipedia URL or search your browser history separately. This speedup is well worth the relatively shallow learning curve.
I find it pretty stupid to compare this feature with Windows' "adaptive menu" feature. There's only a superficial resemblance. Remember, the traditional address bar still "learns" in the way you hate by ordering URLs by the frequency with which you visit them. What is it with the Slashdot crowd and being insanely conservative about their software?
Re:I tried Firefox 3 today (Score:5, Informative)
I think I understand.
You see, the new location bar learns. Though this silly new 'innovation' does indeed search through the URLs *and* titles of bookmarks and history, it also learns what you select the most. Give it a few more days and slashdot should come to the top of the list.
I experienced the same thing in the beginning.
When I bookmark page now I try to throw on a couple common sense tags that way when I type the tag in the location bar in the future, those bookmarks come out on top.
If you're *really* dead set on the shortest route:
1) Click Bookmarks -> Show All Bookmarks
2) Find the slashdot bookmark and select it
4) Click "More" under properties
5) Make the keyword
6) Close the window
Now type
Re:I tried Firefox 3 today (Score:4, Informative)
Next time, try it like this: "LMAO. You are a worthless, pathetic piece of shit. The word you're looking for is voilà, literally 'see there' in French, an idiom used to mean 'there you go'". (though the OP's spelling is pretty damn close to the correct phonetical spelling \vwä-'lä\)
Re:I tried Firefox 3 today (Score:5, Funny)
Expect to find it in a GWB-approved dictionary any day now.
Re: (Score:3, Informative)
Safari is getting up there (Score:4, Informative)
The Safari team recently introduced some native javascript functions [webkit.org], which showed very impressive speed. It looks like the next release Safari will be up there as well (if not even faster still).
I'm off to download the latest Firefox to see how the two compare (on both Windows and OS X platforms).
Re: (Score:3, Interesting)
Firefox 3 also supports new Java plug-in (Score:5, Informative)
Firefox 3 is going to include support for the new Java SE 6 runtime environment.
This is a new implementation of the Java Plug-In that features increased reliability, ability to specify large heap sizes, ability to select a specific JRE version to execute a particular applet, and support for signed applets on Windows Vista.
The New Plug-in is designed to work with: - Internet Explorer 6 and 7 on Windows XP and Windows Vista - Firefox 3 on Windows XP, Windows Vista, Solaris and Linux
Personally, I've been wanting to use the Firefox 3 beta for some time, primarily because of the performance and speed boosts over Firefox 2, but my favourite add-ons still aren't compatible.Note: The new Plug-in does not work with Firefox 2, and no support is planned for this browser with the New Plug-in.
Builds for Windows and Linux available (Score:4, Informative)
Comment removed (Score:3)
Re: (Score:3, Informative)
Microsoft's Biggest Mistake (Score:5, Interesting)
Re:Microsoft's Biggest Mistake (Score:5, Insightful)
Re:Microsoft's Biggest Mistake (Score:4, Interesting)
Take a look at Functional JavaScript [osteele.com]. Extensions for functional programming.
Or the great Prototype [prototypejs.org]Library. Note the functions like 'reduce' that can apply to array.
OS X Results - Spoiler Safari Wins (Score:5, Informative)
Well someone had to, so I ran the numbers for OS X. All of the below were on OS X 10.5.2 running on a MacBook:
I guess if you're a Safari or Firefox person you can look forward to some really fast Javascript performance either way.
Re:OS X Results - Spoiler Safari Wins (Score:4, Informative)
Replying to my own post, I probably should have included Firefox 2.0.0.12 as well. Here are the numbers for that and Firefox 1.5.0.8 which is still on my machine for testing purposes.
Re: (Score:3, Informative)
I think comparing firefox3b4p to webkit is like comparing apples and oranges. Firefox3b4p is a beta version of an actual product, whereas webkit is a rendering engine.
That's why that line in my comparison reads, "Safari with Nightly Webkit r30628." Safari is an actual browser, I just replaced the back end. It's not like I'm going to write my own minimalist front end for it, after all, when it is so easy to plug into Safari. In fact, if anything I'd say Firefox was getting the advantage since I tested the newest versions of their front end and back end whereas I used the old front end for Safari which could, theoretically, be optimized to work better with the latest ve
Is this a legitimate benchmark for a browser? (Score:4, Interesting)
JSON, code decompression, and traversing XML are things that a browser does with JavaScript, some more often than others. Even in those cases, I wouldn't be surprised if browsers had parsers that 'helped' the common browser JavaScript tasks with faster native-library interfaces instead of purely native JavaScript interpretation.
Re: (Score:3, Insightful)
Only if you don't use https, or NTLM, or Kerberos (all browser supported mechanism that don't require javascript). Depending on javascript for encryption is silly.
MD5 is extremely broken for passing passwords about.
stalling (Score:4, Insightful)
Re:stalling (Score:5, Interesting)
Have they discovered threads yet? (Score:5, Insightful)
Re:Have they discovered threads yet? (Score:5, Interesting)
Who cares about Javascript performance when a single script running at any speed can freeze the entire browser?
Or a few Youtube tabs can slow the browser to a halt? (Hint: Firefox REALLY need to delegate Flash rendering to an external process, something I can renice 19. Just like how Konqueror uses nspluginviewer)
Re:Have they discovered threads yet? (Score:5, Insightful)
How about just implementing it? No magic needed. If the whole UI is slow and tends to lock up because it uses only a single thread, and the reason for that is that the language/runtime the UI is written in doesn't support threads, then you have three options:
- keep everything as it is, maybe pretend the problem doesn't exist
- rewrite in a language that does support threading
- extend Javascript resp. its runtime/libraries to support threading
The last one is probably the best option if you want to solve the problem, minimize the amount of work required to do so, and don't want to force all the plugin writers to use another language.Not really what matters to me ... (Score:4, Interesting)
What I find more important are the lockups I get because of limitations to multi-threading in FF, at least under Linux. There are situations where one window locking up means all windows lock up. There are situations where some initial connection to a host being stuck means all of the browser locks up. One can only guess, because FF does not indicate what the problem is -- but more frequently than is funny, I have FF get unresponsive, not re-painting windows anymore and just eating up CPU and memory without reacting until I kill it.
This sucks and this doesn't seem to have changed in FF 3.
Focusing on the wrong aspects (Score:5, Interesting)
What matters to me is the imperfect implementation of Flash (it's not really their responsibility but it is their problem) which often eats up 100% CPU from random flash objects or causes firefox to freeze. Another annoyance is Firefox being frankly poor at displaying large HTML files (when you go on websites with insanely large lists for instance). Where as IE and Opera display these as the page is downloaded. Firefox, for me, freezes, much like notepad will when you open a 2meg+ file . Sometimes it'll recover and display the page after a minute or so, sometimes I have to ctrl+alt+delete.
Re:Focusing on the wrong aspects (Score:4, Insightful)
The fact that Firefox, being an XUL application, has significant chunks of core code written in JavaScript, is probably the main reason why this matters very much. Even if you never visit a site in the wild that uses JavaScript or run with JavaScript totally disabled, you should still see some general improvements in Firefox's performance.
Re:It still doesn't run on my computer (Score:4, Informative)
Back up your Firefox Profile [mozilla.com] and start clean.
Comment removed (Score:5, Insightful)
Re:Firefox Performance (Score:5, Informative)
I could have sworn that PDF was Portable Document Format. All your other points about it are correct though.
Re: (Score:3, Insightful)
Re:Firefox Performance (Score:4, Informative)
Um, PDFs can be made just as accessible as HTML documents [alistapart.com], and Adobe's PDF tools have good integrated support for assistive technologies [adobe.com] built in.
PDF accessibility is a lot like HTML accessibility; you have to know what you're doing to make it happen, but you can make it happen.
Re: (Score:3, Informative)
a) efficient networking
b) lexical analysis
d) parsing.
e) DOM tree construction (required because it's available to javascript)
f) javascript lexical analysis
g) javascript grammar parsing
h) javascript compilation to bytecode
j) javascript execution by vm (including subtasks: initialization, execution, security checks, etc)
k) rendering output
It's pr
Re: (Score:3, Informative)
Re: (Score:3, Informative)
If the memory in question are rendered page caches, which aren't going to get touched unless they're viewed. As long as the allocation tables are efficiently indexed, i don't see how memory usage is directly related to speed.
Re:Memory leak? (Score:4, Funny)
Re:Memory leak? (Score:5, Informative)
Re:Memory leak? (Score:5, Funny)
Once upon a time there was this OS named Windows Millennium Edition, also known as "the" in your examples above.
Re:JavaScript, huh. (Score:5, Insightful)
Re: (Score:3, Insightful)
Re:OSX? (Score:5, Insightful)
Open-Source seems good for getting a job 90% finished and completely ignoring the 10% polish required to make it an app of the same quality as closed-source
Re: (Score:3, Insightful)
Re:How about the frickin' memory? (Score:4, Insightful)
Mark this as off-topic if you like. I'm responding partially to the parent comment, but mostly to its score and reason.
This is a discussion board. How can you mark someone's comment as redundant? Is this an attempt to invalidate their statement? Don't blame them when it's actually a limitation of the forum system. There is no simple way to increment an "I agree" or "I have the same problem" counter, there has to be a new comment for each person who agrees. There is no way of adding weight to a comment except by increasing child nodes, or adding as many individual argument nodes that are similar. Yes, there is already one branch in this thread that talks about the memory issues, but relax not everyone perfectly gets all their statements in exactly the right location in the discussion tree. Judge it simply on what it says, not the comments location.
For what it's worth, I agree. I also have problems with memory bloating with FF. I don't really care if they are memory leaks, or memory fragments, it's still a problem that I would like to see fixed. Unfortunately I cannot fix the problem, so I will patiently wait for the next great release of FF. I have no solution, but this is my informal bug report.
Increase in speed on JavaScript will be great. There are many times when my FF instance gets temporarily grayed out when it loads a page with lots of JavaScript. This is the window manager thinking that FF is locked up and not responding.
Re: (Score:3, Informative)
We already have a perfectly good one. It's called HTTP. While the acronym may be misleading, it has nothing to do with HTML. In fact, no protocols (that I know of) have anything implicit to do with HTML.
I agree that we should be getting the damn code out of your hypertext, but that doesn't necessitate a new protocol.
Re:About time (Score:5, Insightful)
Re: (Score:3, Informative)
I realise that it mostly is amazing, and I'm not satisfied with Firefox by any means, but Opera just feels alien; a bit like when you start messing about with WINE a
Re: (Score:3, Insightful)
Re:CPU hogging bug fixed? (Score:4, Insightful)
I'm pretty sure it has to be a combination of minor flaws in Firefox (as not every program I run has this issue), Windows XP (with memory handling far better than previous versions, but still not exactly the gold standard of memory management), and all the myriad changes to my system's configuration over time.
It does it on both my work computer and my home computer. Then again, they're both XP Pro machines. They're very different in terms of hardware, which tentatively rules out a specific hardware config. The memory on my home machine is double that of my work machine, but the highpoint seems to be about the same - so I doubt it has much to do with total system memory. What sites I hit seems to have no relevance. The only other common factor I can think of is that I run NoScript on both - though if I remember right the problem predated my use of that (I first noticed it a while back, and had actually hoped 2 would fix it).
The main issue seems to be that a specific amount of memory is eaten up when you open a site in a tab - but closing that tab often doesn't clear up the space. I just now closed every tab except Slashdot - and it went from 157mb (when I had 14 tabs open) to a minuscule 153mb. From experience, waiting for it to dump cache is ineffective. If I close the program, the memory clears itself just fine - but only if there is no other Firefox window open. I'm guessing that multiple Firefox app windows share a footprint.
Then again, saying "all" of my memory was an exaggeration. I've rarely seen it hold on to much more than 150mb after closing all but one window, though if I go on for very long without at least shutting down firefox, that minimum can creep up - and on a few occasions really has taken more memory than I actually have on my machine (virtual cache trash time). It's also probably not a noticeable problem unless you're a heavy multitasker (in which case that footprint becomes painfully obvious).
I've noticed it doesn't happen on my fiance's Vista machine, or on any 2003 Server boxes I've run it on. It may be a problem that only occurs on XP, or it just doesn't like the way I smell.
However, if you are able to reproduce it, you'll see it happen whenever more than one tab has been opened. Opening one tab, then clearing it, seems to work - but once a second tab opens, clearing the original tab clears it's footprint, but any tab opened after that exhibits the problem.